Predictive Value of Neuronal Apoptotic Bodies in Cerebrospinal Fluid for the Differential Diagnosis of Bacterial from Viral Meningitis

Predictive Value of Neuronal Apoptotic Bodies in Cerebrospinal Fluid for the Differential Diagnosis of Bacterial from Viral Meningitis | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Predictive Value of Neuronal Apoptotic Bodies in Cerebrospinal Fluid for the Differential Diagnosis of Bacterial from Viral Meningitis Shohreh Farshad, Seyedeh Sedigheh Hamzavi, Maral Choopanizadeh, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8095123/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 10 You are reading this latest preprint version Abstract Introduction: Rapid and accurate differentiation of bacterial and viral meningitis is critical for effective treatment but remains challenging. To address this, our study investigated the frequency of apoptotic bodies in cerebrospinal fluid (CSF) as a potential diagnostic biomarker to distinguish the cause of infection. Materials and Methods The study was conducted on 1115 CSF samples collected from patients clinically suspicious of meningitis. CSF was directly analyzed to evaluate leukocyte count, protein, and sugar concentration, and to determine bacterial causative agents using direct smear, Gram staining, and culture on blood and chocolate agar. Furthermore, to determine viral meningitis, PCR was used to detect the presence of viral agents such as Herpes simplex virus type 1 (HSV-1) and Enterovirus (EV). Given the leukocyte count, the samples were divided into CSF with less or more than 5 leukocytes per ml as negative and positive CSF, respectively. Then CSF was assessed for the frequency of small particles as neuronal apoptotic bodies stained with fluorochrome-labeled anti-CD24 and CD54 antibodies and intracellular staining of Choline acetyltransferase (ChAT) and Tyrosine hydroxylase (TH) using flow cytometry. Results Out of 1,115 analyzed CSF samples, 77 were positive (WBC ≥ 5/mm³), and 77 negative samples (WBC < 5/mm³) were randomly selected as controls. Within the positive group, the causes of infection were identified as bacterial for 10 samples, viral for 12, and the cause remained unknown for 55 samples. No significant differences were observed in the levels of CD24+, CD54+, or CD24/CD54 + apoptotic bodies—which express the neuronal markers ChAT and TH—across the bacterial, viral, and unknown cause (UC) infection groups. Despite this, their frequencies were substantially elevated in all positive CSF samples compared to negative controls. Conclusions While the levels of apoptotic bodies in CSF can differentiate between samples with pleocytosis (WBC ≥ 5/mm³) and those without, they cannot distinguish bacterial from viral meningitis. This suggests that the elevation in neuronal particles is likely a nonspecific consequence of leukocyte recruitment into the CNS and subsequent neuronal apoptosis, rather than a pathogen-specific response or a marker of patient survival. Furthermore, the low incidence of confirmed bacterial and viral meningitis in our study may have influenced these results. Meningitis Differential diagnosis Biomarkers Apoptosis Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction The life-threatening inflammation of the meninges known as meningitis necessitates rapid diagnosis and treatment. Its etiologic agents are diverse, encompassing bacterial pathogens such as Neisseria meningitidis , Streptococcus pneumoniae , and Haemophilus influenzae , as well as viral pathogens like enteroviruses and herpes simplex virus . Less commonly, it can be induced by varicella-zoster virus , mumps virus , or HIV [ 1 , 2 ]. The bacterial form of meningitis is more severe than its viral counterpart and requires immediate treatment to prevent serious complications and high mortality [ 3 ]. While the differentiation of these two meningitis types depends on clinical findings, imaging, and CSF analysis (including cell counts, protein/glucose levels, and bacterial culture or PCR), these laboratory methods are often time-consuming and can produce inconclusive results [ 4 , 5 ]. Beyond the significant clinical similarities between bacterial and viral meningitis, overlapping CSF findings can further complicate diagnosis, making it impossible to determine the type based on symptoms alone [ 6 , 7 ]. The frequent contraindication of lumbar puncture (LP) in severely ill patients further complicates diagnosis [ 8 ], which can delay the initiation of targeted therapy, promote unnecessary antibiotic use, and contribute to the development of antibiotic resistance [ 9 ]. Given these diagnostic challenges, identifying biomarkers to distinguish bacterial from viral meningitis could provide a valuable adjunct to conventional methods. Biomarkers reflecting key pathophysiological processes—such as inflammation, immune response, and microbial infection—offer the potential for rapid and accurate differentiation, guiding timely treatment. Promising candidates include acute-phase reactants like C-Reactive Protein (CRP) and Procalcitonin (PCT), pro- and anti-inflammatory cytokine profiles [ 10 ], Neutrophil Gelatinase-Associated Lipocalin (NGAL) [ 11 ], and various microRNAs and other nucleic acids [ 12 ]. Pathogens in bacterial meningitis trigger a strong CNS inflammatory response, which causes major breakdown of the blood-brain barrier (BBB) and amplifies the release of inflammatory signals [ 13 ]. This process activates several cell death mechanisms, including apoptosis, necrosis, and pyroptosis (a specific type of programmed cell death via inflammasomes). The combination of severe inflammation, tissue hypoxia, and direct bacterial injury enhances apoptosis in neuronal cells, causing widespread damage and cell death [ 14 ]. Viral meningitis generally induces a milder inflammatory response than bacterial meningitis, a distinction underpinned by its pathophysiology. Causative viruses, such as enteroviruses and HSV, are typically confined to the meninges and subarachnoid space, avoiding the aggressive parenchymal invasion seen with bacteria. Although apoptosis is initiated to clear infected cells, the response is more controlled and selective. This precision, often mediated by mechanisms like caspase-3 activation, targets infected cells while sparing healthy neural tissue, resulting in substantially less neuronal apoptosis and cell loss. Consequently, this limited cellular damage explains the characteristically less severe clinical presentation and lower risk of long-term neurological dysfunction in viral meningitis [ 15 ] [ 16 , 17 ]. A multimodal approach that combines apoptotic markers with traditional biomarkers (CRP, procalcitonin, cytokines) offers superior diagnostic precision for differentiating bacterial from viral meningitis compared to any single marker [ 18 ]. Due to their small size (50-5000 nm in diameter), apoptotic particles were distinguished from intact cells by their light scatter properties using flow cytometry. This study aimed to evaluate the frequency of neuronal-derived particles—specifically those containing the intracellular enzymes tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) and expressing the surface markers CD24 and CD54—in the cerebrospinal fluid (CSF) of meningitis patients to discriminate between bacterial and viral causes. Material and methods Study population The study population was selected from 1,115 patients with suspected meningitis. After patients were diagnosed by an infectious disease physician and provided written informed consent, cerebrospinal fluid (CSF) samples were collected into three sterile tubes. These samples were then transported to the Professor Alborzi Clinical Microbiology Research Center (PACMRC), Shiraz University of Medical Sciences, Shiraz, Iran, for analysis. One CSF tube was centrifuged at 5000 ×g for 5 minutes; the pellet was subjected to Gram staining and cultured on blood and chocolate agar to identify bacterial pathogens. The second tube was used for total white blood cell (WBC) count, and based on a threshold of ≥ 5 WBCs/mm³, 77 samples were selected for real-time PCR to detect viral agents, including Herpes simplex virus type 1 and Enterovirus. From the samples with WBC < 5 cells/mm³, 77 were randomly selected as controls and, like the case samples, underwent RT-PCR testing for viral agents (Fig. 1 ). The third CSF tube was used for biochemical analysis (protein and glucose levels). Concurrently, patient blood samples were collected for complete blood count and other parameters (Table 1 ). Quantification of neuronal apoptotic bodies in CSF For the semi-quantitative analysis of CD24 + and CD54 + apoptotic bodies, cellular debris and large particles (> 5000 nm) were first removed from 1 mL CSF samples by centrifugation at 250 × g for 5 minutes. The pellet containing apoptotic bodies was re-suspended and stained extracellularly with 5 µl of fluorescently-labeled anti-CD24-PE and anti-CD54-PerCp antibodies (Biolegend, USA) for 20 minutes in the dark. After washing with phosphate-buffered saline (PBS), the samples were fixed and permeabilized with 200 µl of permeabilization buffer for 20 minutes at 4°C. For intracellular staining, the particles were incubated with 5 µl of primary antibodies against choline acetyltransferase (ChAT) and tyrosine hydroxylase (TH) (1 µg/mL) for 20 minutes at 4°C. Following a PBS wash, the samples were incubated with 5 µl of FITC-conjugated anti-IgG secondary antibody for 20 minutes at 4°C. After a final wash with PBS, the stained apoptotic bodies were resuspended and analyzed using a flow cytometer (BD FACSCalibur, USA). The complete procedures for apoptotic body isolation, staining, and the gating strategy are illustrated in Fig. 2 and Fig. 3 . Statistical analysis Data were analyzed using SPSS Statistics (Version 23; IBM, Armonk, NY, USA). Categorical variables, such as gender and culture results, are presented as frequencies and were compared between groups using the Chi-square test. Continuous variables, including CSF biochemical parameters (e.g., protein, glucose), apoptotic body levels, and blood parameters (e.g., WBC, NLR, CRP, ESR), are presented as mean ± standard deviation or median with interquartile range, as appropriate. The Student's t-test (or Mann-Whitney U test, if normality was violated) was used to compare these continuous variables between the two study groups and to assess their association with meningitis outcomes. A p-value of < 0.05 was considered statistically significant. Graphs were generated using GraphPad Prism (Version 9; GraphPad Software, San Diego, CA, USA). Results Peripheral blood and CSF parameters One hundred and eighty four subjects were selected from 1,115 patients with suspected meningitis: 77 patients with CSF pleocytosis (WBC ≥ 5/mm³) and 77 controls with normal CSF WBC counts (< 5/mm³). The groups were well matched in terms of age and gender (Table 1 ). Comparative analysis of peripheral blood samples revealed that systemic inflammatory markers, including WBC, Neutrophil to lymphocyte ratio (NLR), and ESR were significantly elevated in the group with WBC ≥ 5/mm 3 in CSF. Analysis of CSF further showed a characteristic profile in patients, with significantly increased protein and decreased glucose concentrations compared to controls (Table 1 ). Table 1 Baseline characteristics and laboratory findings of patients grouped by CSF pleocytosis status (WBC ≥ 5/mm³ vs. < 5/mm³). NA: Not Applicable. CSF (WBC) ≥ 5 < 5 P Age (Y) 22.3 ± 23.5 y 20.6 ± 21.5 y 0.64 Gender Male 36 (47) 37 (49) 0.87 Female 41 (53) 40 (51) Blood WBC 10.8 ± 5 8.1 ± 3.5 0.0001 NLR 6.5 ± 6.2 2.5 ± 2.5 0.0001 Mix 5.6 ± 2.4 6.7 ± 2.9 0.07 ESR 47.3 ± 35.5 25.8 ± 29 0.02 Sugar 110 ± 36 117 ± 46 0.35 CRP 38.3 ± 49 36 ± 27 0.85 Positive BC 8 1 0.001 CSF Sugar 46.8 ± 24 67 ± 13.3 0.0001 Protein 182 ± 306 42 ± 35 0.0001 Total count 12838 ± 42556 NA NA WBC 482 ± 1286 NA NA NLR 3.7 ± 9.3 NA NA CD24 + particles 174 ± 258 64.5 ± 73.5 0.001 CD54 + particles 98 ± 311 76 ± 67 0.764 CD24+/CD54 + particles 148 ± 249 137 ± 163 0.749 Association between etiologic agents, laboratory findings, and mortality Blood culture analysis revealed a significantly higher positivity rate in the pleocytosis group (10.4%, 8/77) compared to the control group (1.3%, 1/77), with an overall positivity rate of 5.8% (9/154). Of the 1,115 CSF samples cultured, 12 (1.07%) were positive. All confirmed bacterial growth was isolated from patients in the CSF-positive group, with no positive cultures detected in the control group. Analysis of CSF by molecular method to determine the viral causative agents of meningitis revealed that 18 (1.6%) CSF were positive with viral agents. Of these, eight (10.4%, 8/77) samples were in CSF positive group and 10 (13%, 10/77) samples were in the CSF negative group. Table 2 represents the frequency of blood and CSF culture and its comparison between CSF positive and negative groups. Of the 77 positive CSF, 57 (74%) samples were negative for bacterial and viral agents therefore we defined this group as unknown cause (UC). Table 2 Comparison of bacterial and viral agents detected in blood and CSF between CSF with WBC count < 5 (CSF negative) and ≥ 5 cells /mm 3 (CSF positive). CONS: Coagulase negative staphylococci. The P value indicates a significant difference in bacterial culture yields from blood and CSF between the CSF-positive and CSF-negative groups. No (%) CSF + No (%) CSF – No (%) P value Blood culture (154) No growth 145 (94) 69 (89.6) 76 (98.7) 0.001** Salmonella sp. 1 (0.7) 1 (1.3) 0 CONS 7 (4.5) 6 (7.7) 1 (1.3) Enterococcus Sp. 1 (0.7) 1 (1.3) 0 CSF (154) Culture No growth 140 (91) 65 (84.4) 77 (100) 0.005** Acinetobacter sp. 4 (2.6) 4 (5.2) 0 Bacillus sp. 2 (1.3) 0 0 Enterococcus sp. 1 (0.65) 1 (1.3) 0 CONS 3 (1.9) 3 (3.9) 0 Proteus sp. 1 (0.65) 1 (1.3) 0 Salmonella 2 (1.3) 2 (2.6) 0 S. pneumoniae 1 (0.65) 1 (1.3) 0 PCR Negative 136 (88.3) 69 (89.6) 67 (87) HSV 13 (8.4) 4 (5.2) 9 (11.7) 0.8 Enterovirus 5 (3.3) 4 (5.2) 1 (1.3) Assessment of the association between meningitis etiology and laboratory parameters revealed no statistically significant differences in neutrophil counts, or the NLR, across bacterial, viral, and UC groups. This was despite observed trends where bacterial cases showed higher neutrophils. Additional findings indicated markedly elevated lymphocyte counts in viral meningitis CSF, contrasting with the lower glucose and higher protein levels characteristic of bacterial meningitis (Table 3 and Fig. 4 ). Table 3 Comparison of CSF parameters between different etiologies of meningitis. P1 represents differences between Bacterial vs. Viral, P2 : Bacterial vs. unknown cause (UC), P3: Viral vs. UC CSF Bacterial Viral UC P1 P2 P3 WBC (Cells/mm 3 ) 668 ± 1047 685 ± 1903 371.7 ± 1161 0.98 0.41 0.47 Neutrophils (%) 48.1 ± 37.7 23.5 ± 35.8 28.6 ± 35.7 0.24 0.2 0.74 Lymphocytes (%) 28.3 ± 29.7 66.5 ± 39.5 47.4 ± 41.3 0.05 0.12 0.29 NLR 3.8 ± 6 1.7 ± 3.6 3.9 ± 6 0.45 0.97 0.6 Sugar (mg/dl) 36.3 ± 25.7 55.8 ± 19.1 48 ± 23.4 0.05 0.14 0.29 Protein (mg/dl) 261.6 ± 272 43.7 ± 53.8 181 ± 328 0.033 0.47 0.005 Analysis of mortality associated with meningitis etiology indicated that all fatalities were confined to the CSF-positive cohort. Specifically, bacterial meningitis accounted for 25% (n = 2) of deaths, while the majority (75%, n = 6) were of unknown origin (Fig. 5 ). Association between CSF neuronal apoptotic body levels and patient clinical outcomes Analysis of neuronal apoptotic bodies based on WBC count revealed that CSF samples with ≥ 5 cells/mm³ had significantly higher frequencies of ChAT+/TH + CD24 + apoptotic bodies. In contrast, the frequencies of ChAT+/TH + CD54 + and ChAT+/TH + CD24 + CD54 + particles showed no significant difference between the high and low WBC groups. Evaluation of apoptotic body frequency in the CSF showed no statistically significant association with the etiology of meningitis (bacterial, viral, or unknown), as detailed in Table 4 and Fig. 6 . In addition, no significant differences were observed in the frequency of neuronal apoptotic bodies when compared across the different bacterial and viral etiologies of meningitis (Table 5 ). Table 4 Comparing the levels of apoptotic body in the CSF with different characteristics. P1 : CSF with WBC ≥ 5 vs . WBC < 5, P2 : Bacterial vs. viral meningitis, P3 : Bacterial vs. unknown cause of meningitis, P4 : Viral vs. unknown cause of meningitis, P5 : Survivors vs. non-survivors. Group CD24+ CD54+ CD24 + CD54+ CSF WBC ≥ 5 174 ± 258 98 ± 311 148 ± 284 WBC < 5 64 ± 73 86 ± 66 137 ± 162 Bacterial 104 ± 113 94 ± 127 197 ± 321 Viral 86 ± 127 79 ± 72 119 ± 81 UC 186 ± 287 103 ± 353 138 ± 287 Survivor 112 ± 201 94 ± 230 145 ± 236 Non-survivor 105 ± 86 63 ± 40 99 ± 92 P1 0.0001 0.7 0.7 P2 0.7 0.7 0.4 P3 0.3 0.9 0.5 P4 0.17 0.8 0.8 P5 0.8 0.7 0.6 Table 5 Apoptotic body levels in CSF by infectious cause. DM; Diagnostic method, CONS; Coagulase Negative Staphylococci, HSV; Herpes simplex virus Sample DM Cause No. CD24+ CD54+ CD24 + CD54+ CSF Culture Acinetobacter sp. 4 69 ± 16 72 ± 18 93 ± 79 Bacillus sp. 2 31 ± 19 57 ± 30 106 ± 97 Enterococcus sp. 1 235 46 281 CONS 3 145 ± 125 39 ± 28 222 ± 338 Proteus sp. 1 378 131 1161 Salmonella 2 17.2 ± 3.5 46.5 ± 48 19 ± 7 S. pneumoniae 1 28.4 520 37 PCR HSV 13 87 ± 118 93 ± 77 127 ± 71 Enterovirus 5 112 ± 167 35 ± 18 131 ± 133 Evaluation of the association between apoptotic body frequency and patient outcome showed that the levels of ChAT/TH + CD24+, CD54+, and CD24 + CD54 + particles were not significantly different between survivors and non-survivors, although they were numerically higher in survivors (Table 3 and Fig. 7 ). Discussion Differentiating bacterial meningitis from viral meningitis is one of the main challenges for physicians in order to prescribe the most effective medication at the right time. Nevertheless, despite all the efforts made, in cases where bacterial culture and molecular methods fail to identify the causative agents of meningitis, and laboratory findings yield inconclusive results, differential diagnosis remains uncertain and ambiguous. Considering that previous research has demonstrated greater tissue damage in bacterial meningitis compared to the viral form, often leading to more serious complications [ 19 ], this study aimed to assess the frequency of ChAT/TH + particles expressing CD24 and CD54 molecules (reflecting neuronal and immune cell markers released during the progression of meningitis) in CSF of patients meningitis with different etiologies. Regarding the CSF analysis, WBC count showed that bacterial growth was substantially more frequent in the CSF-positive (WBC ≥ 5cells/mm 3 ) group, indicating a significant association between elevated WBC counts and bacterial infection. In contrast, viral infection showed no such association, while the results for meningitis with unknown cause (UC) fell between those of bacterial and viral forms. Furthermore, CSF protein and sugar were significantly different in CSF-positive group compared with those in CSF-negative group (WBC < 5cells/mm 3 ). A comparison of WBC subpopulations, including neutrophils, lymphocytes, and the neutrophil-to-lymphocyte ratio (NLR), across meningitis cases with different etiologies (bacterial, viral and UC) revealed no statistically significant differences between the study groups. Nonetheless, subtle trends were noted in which bacterial meningitis cases tended to show higher neutrophil counts, while viral meningitis cases exhibited relatively elevated lymphocyte levels. In a previous study with a substantial infant sample size, neutrophil predominance in CSF showed the strongest association with the diagnosis of bacterial meningitis [ 20 ]. Another study on neonates and infants aged 1–3 month reported that a cerebrospinal fluid (CSF) neutrophil count of 2×10⁶/L or higher was independently associated with a higher probability of bacterial meningitis, with positive likelihood ratios of at least 5 and 3, respectively [ 21 ]. Cluster of differentiation 24 (CD24) is a small, heavily glycosylated adhesion protein expressed on immune, epithelial, neural, and muscle cells [ 22 ]. Furthermore, this molecule highly expressed on immature T cells, but its expression declines upon maturation. However, following T cell activation, CD24 is rapidly upregulated and plays a critical role in promoting optimal activation and survival of certain T cell subsets in peripheral lymphoid organs and the central nervous system [ 23 ]. This cell surface protein (CD24) interacts with multiple receptors, including P-selectin, Siglec-10, and β1 integrin. Through its engagement with these receptors and its association with the Notch signaling pathway, CD24 regulates key cellular processes such as adhesion, migration, differentiation, and apoptosis [ 24 ]. Analysis of CD24 + particles in CSF demonstrated significantly higher frequencies in bacterial meningitis and unspecified meningitis compared to negative CSF controls [ 25 ]. Although CD24 + particle levels were more frequent in bacterial meningitis compared to viral meningitis, the difference was not statistically significant, indicating that CD24 lacks sufficient discriminatory power to differentiate between these etiologies. Furthermore, CD24 levels showed no significant association with clinical outcomes (survival vs. non-survival) in meningitis patients. The CD54 molecule, also known as intercellular adhesion molecule 1 (ICAM-1), is constitutively expressed on neurons [ 26 ] and endothelial cells at low levels and can be induced on antigen-presenting cells, T cells, and B cells upon stimulation. It plays a crucial role in leukocyte adhesion and immune activation. ICAM-1 binds to the β2 integrin lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18), a key interaction that facilitates immune cell migration and triggers inflammatory responses [ 27 , 28 ]. Based on its role in the immune responses, we compared the concentration of particles expressing CD54 in CSF between bacterial and viral meningitis groups. CD54 levels were not significantly different between the bacterial and viral meningitis groups, despite an observed increase in the bacterial group. Importantly, both meningitis groups (bacterial and viral) exhibited significantly higher CD54 levels compared to the negative controls. Furthermore, CD54 level was not significantly different between survivors and non-survivors patients. Given the observed increase of leukocytes in the CNS during meningitis, the upregulation of CD54 + particles may result from apoptosis induced in brain endothelial cells and leukocytes combating pathogens. A recent study focused on brain microenvironment endothelial cells revealed a key defense mechanism against meningitis. It showed that caspase-8 mediated apoptosis helps recruit neutrophils, which are essential for pathogen clearance [ 29 ]. Therefore, it seems that apoptosis can be useful in the infiltration of leukocytes and activation and contraction of immune responses and consequently meningitis regression. However, CD54 and CD24 expressing particles in our study were not significantly different between bacterial and viral induced meningitis. While bacterial interaction with neurons causes neuroinflammation and neuronal death [ 30 ], we found no significant difference in the presence of neuronal enzymes (ChAT and TH) [ 31 , 32 ], on CD24/CD54-expressing particles between bacterial and viral meningitis cases. Given that, neuronal damage is the major consequence of bacterial and in less extent viral meningitis, it seems that the levels of CD24 + and CD54 + particles expressing TH and CHAT be more frequent in bacterial compared to viral meningitis. However, no significant difference was observed between the two study groups or between survivors and non-survivors. The limited number of bacterial and viral positive samples, a key limitation of the study, likely accounts for this discrepancy. Conclusion Although apoptosis is a major outcome of bacterial and viral meningitis, we observed no significant difference in CD24/CD54 + TH/CHAT + particle levels between the bacterial and viral groups, or between survivors and non-survivors. However, a substantial increase was observed in CSF-positive samples (WBC ≥ 5 cells/µL) compared to CSF-negative samples (WBC < 5 cells/µL). This suggests that the elevated particle levels are likely a consequence of leukocyte recruitment into the CNS and subsequent neuronal apoptosis, rather than a specific response to the type of pathogens or patient survival. Declarations Ethics approval and consent to participate This study was approved by the Ethics Committee of the National Institute for Medical Research and Development (NIMAD) with the code IR.NIMAD.REC.1397.096. All procedures were performed in accordance with the relevant guidelines and regulations. Consent for publication Not applicable. Competing interests The authors declare no competing interests. Clinical trial number Not applicable. Fundings This work was supported by the NIMAD under grant number 971220 and by PACMRC under grant number 97 − 2. Author Contribution S.F. and S.S.H. contributed equally to this work. Me.K. conceived and designed the study. S.F., S.S.H., M.C., Ma.K., and Z.J. were responsible for data collection and investigation. M.C. and Me.K. performed the laboratory experiments and flow cytometry. S.F. and S.S.H. conducted data analysis. Me.K. supervised the project and acquired funding. The manuscript was drafted by S.F., S.S.H., and Z.J. and critically reviewed and edited by all authors. All authors have read and agreed to the published version of the manuscript. Acknowledgement We extend our sincere gratitude to the National Institute for Medical Research and Development (NIMAD) and the Professor Alborzi Clinical Microbiology Research Center (PACMRC) for their generous support of this study. 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Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 02 Feb, 2026 Reviews received at journal 05 Jan, 2026 Reviews received at journal 27 Dec, 2025 Reviewers agreed at journal 21 Dec, 2025 Reviewers agreed at journal 19 Dec, 2025 Reviewers invited by journal 12 Dec, 2025 Editor invited by journal 14 Nov, 2025 Editor assigned by journal 14 Nov, 2025 Submission checks completed at journal 14 Nov, 2025 First submitted to journal 12 Nov, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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12:31:04","extension":"html","order_by":39,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":135413,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8095123/v1/bc58ffa74e05f9c7b83b8610.html"},{"id":98750032,"identity":"73d000a9-04e4-4f3b-8875-43028910d683","added_by":"auto","created_at":"2025-12-22 09:07:07","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":70010,"visible":true,"origin":"","legend":"\u003cp\u003eFlow chart illustrating the selection of cases and controls for apoptotic body analysis.\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8095123/v1/51b443f4bd92ca3263b15074.jpg"},{"id":98780040,"identity":"13e4c689-5a78-4c07-bd11-25591d888950","added_by":"auto","created_at":"2025-12-22 12:30:59","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":51458,"visible":true,"origin":"","legend":"\u003cp\u003eProtocol for the staining and analysis of CD24+ and CD54+ apoptotic bodies in CSF. Steps include: (1) Initial centrifugation of 1 mL CSF at 250 ×g for 5 min to remove cells and debris. (2) Centrifugation of the resulting supernatant at 3,000 ×g for 20 min to pellet apoptotic bodies. (3) Extracellular staining of the pellet with anti-CD24-PE and anti-CD54-PerCP antibodies. (4) Intracellular staining with anti-ChAT and anti-TH primary antibodies, followed by an FITC-conjugated secondary antibody. (5) Flow cytometric detection and analysis of the stained apoptotic bodies.\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8095123/v1/a1bdd4c08cd9f4511d813e06.jpg"},{"id":98777974,"identity":"2a3efd13-c636-442a-aed0-ff9e5bc8e327","added_by":"auto","created_at":"2025-12-22 12:28:46","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":106951,"visible":true,"origin":"","legend":"\u003cp\u003eFlow cytometric-gating strategy for apoptotic body analysis. The sequence was as follows: (a) Gating on the small particle population based on light scatter properties (intensity \u0026lt;200). (b) Selection of CD24-PE⁺ and/or CD54-PerCP⁺ events from the small particle gate. (c) Final measurement of the frequency of particles positive for the intracellular neuronal markers choline acetyltransferase (ChAT) and tyrosine hydroxylase (TH) within the CD24/CD54-positive populations, presented as a histogram.\u003c/p\u003e","description":"","filename":"Fig3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8095123/v1/68a575676f01b809b1236fe9.jpg"},{"id":98779971,"identity":"83fbbac0-f710-4653-967d-e6a56a2d9b1e","added_by":"auto","created_at":"2025-12-22 12:30:58","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":61103,"visible":true,"origin":"","legend":"\u003cp\u003eThe bars illustrate the frequencies of neutrophils, lymphocytes, and the NLR in the CSF of meningitis patients with different etiologies. UC; Meningitis with unknown cause.\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8095123/v1/14c597bcffcf396197824374.jpg"},{"id":98749995,"identity":"d07699cf-ab5e-472c-b0eb-e77bf4124026","added_by":"auto","created_at":"2025-12-22 09:07:05","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":81281,"visible":true,"origin":"","legend":"\u003cp\u003eSunburst plot depicting patient mortality and the leading causes of death in meningitis. The value preceding \"Death\" indicates the mortality rate within the CSF-positive group. Adjacent values for DUCM (death by unknown cause of meningitis) and DBM (death by bacterial meningitis) represent their prevalence among deceased patients.\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8095123/v1/04e7f57ecbec644856b44766.jpg"},{"id":98777433,"identity":"80499c91-1a6a-4b61-9338-031cff8b6bdc","added_by":"auto","created_at":"2025-12-22 12:27:04","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":612239,"visible":true,"origin":"","legend":"\u003cp\u003eThe bars represent the frequency of ChAT/TH+ particles expressing CD24, CD54 and CD24+CD54 in CSF samples with different etiologies of meningitis in compared with negative CSF (WBC \u0026lt; 5 cell/mm\u003csup\u003e3\u003c/sup\u003e).\u003c/p\u003e","description":"","filename":"Fig5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8095123/v1/59b101a8c7f9768bfb912747.jpg"},{"id":98778789,"identity":"35105cdc-1b44-41d8-ab5b-6d92ea0b9dd2","added_by":"auto","created_at":"2025-12-22 12:29:39","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":187933,"visible":true,"origin":"","legend":"\u003cp\u003eThe bar graphs depict the levels of ChAT/TH+ CD24+ and CD54+ particles among survivors and non-survivors.\u003c/p\u003e","description":"","filename":"Fig7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8095123/v1/b2a005d197c4474a21088601.jpg"},{"id":98783471,"identity":"f943e197-8e4d-48b7-91f4-302025f98f23","added_by":"auto","created_at":"2025-12-22 12:42:00","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2134520,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8095123/v1/40ecd270-b5b0-4f1b-8892-a488d8d0af1d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Predictive Value of Neuronal Apoptotic Bodies in Cerebrospinal Fluid for the Differential Diagnosis of Bacterial from Viral Meningitis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe life-threatening inflammation of the meninges known as meningitis necessitates rapid diagnosis and treatment. Its etiologic agents are diverse, encompassing bacterial pathogens such as \u003cem\u003eNeisseria meningitidis\u003c/em\u003e, \u003cem\u003eStreptococcus pneumoniae\u003c/em\u003e, and \u003cem\u003eHaemophilus influenzae\u003c/em\u003e, as well as viral pathogens like \u003cem\u003eenteroviruses\u003c/em\u003e and \u003cem\u003eherpes simplex virus\u003c/em\u003e. Less commonly, it can be induced by \u003cem\u003evaricella-zoster virus\u003c/em\u003e, \u003cem\u003emumps virus\u003c/em\u003e, or \u003cem\u003eHIV\u003c/em\u003e [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The bacterial form of meningitis is more severe than its viral counterpart and requires immediate treatment to prevent serious complications and high mortality [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. While the differentiation of these two meningitis types depends on clinical findings, imaging, and CSF analysis (including cell counts, protein/glucose levels, and bacterial culture or PCR), these laboratory methods are often time-consuming and can produce inconclusive results [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Beyond the significant clinical similarities between bacterial and viral meningitis, overlapping CSF findings can further complicate diagnosis, making it impossible to determine the type based on symptoms alone [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The frequent contraindication of lumbar puncture (LP) in severely ill patients further complicates diagnosis [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], which can delay the initiation of targeted therapy, promote unnecessary antibiotic use, and contribute to the development of antibiotic resistance [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eGiven these diagnostic challenges, identifying biomarkers to distinguish bacterial from viral meningitis could provide a valuable adjunct to conventional methods. Biomarkers reflecting key pathophysiological processes\u0026mdash;such as inflammation, immune response, and microbial infection\u0026mdash;offer the potential for rapid and accurate differentiation, guiding timely treatment. Promising candidates include acute-phase reactants like C-Reactive Protein (CRP) and Procalcitonin (PCT), pro- and anti-inflammatory cytokine profiles [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], Neutrophil Gelatinase-Associated Lipocalin (NGAL) [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], and various microRNAs and other nucleic acids [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePathogens in bacterial meningitis trigger a strong CNS inflammatory response, which causes major breakdown of the blood-brain barrier (BBB) and amplifies the release of inflammatory signals [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. This process activates several cell death mechanisms, including apoptosis, necrosis, and pyroptosis (a specific type of programmed cell death via inflammasomes). The combination of severe inflammation, tissue hypoxia, and direct bacterial injury enhances apoptosis in neuronal cells, causing widespread damage and cell death [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Viral meningitis generally induces a milder inflammatory response than bacterial meningitis, a distinction underpinned by its pathophysiology. Causative viruses, such as enteroviruses and HSV, are typically confined to the meninges and subarachnoid space, avoiding the aggressive parenchymal invasion seen with bacteria. Although apoptosis is initiated to clear infected cells, the response is more controlled and selective. This precision, often mediated by mechanisms like caspase-3 activation, targets infected cells while sparing healthy neural tissue, resulting in substantially less neuronal apoptosis and cell loss. Consequently, this limited cellular damage explains the characteristically less severe clinical presentation and lower risk of long-term neurological dysfunction in viral meningitis [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA multimodal approach that combines apoptotic markers with traditional biomarkers (CRP, procalcitonin, cytokines) offers superior diagnostic precision for differentiating bacterial from viral meningitis compared to any single marker [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDue to their small size (50-5000 nm in diameter), apoptotic particles were distinguished from intact cells by their light scatter properties using flow cytometry. This study aimed to evaluate the frequency of neuronal-derived particles\u0026mdash;specifically those containing the intracellular enzymes tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) and expressing the surface markers CD24 and CD54\u0026mdash;in the cerebrospinal fluid (CSF) of meningitis patients to discriminate between bacterial and viral causes.\u003c/p\u003e"},{"header":"Material and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003eThe study population was selected from 1,115 patients with suspected meningitis. After patients were diagnosed by an infectious disease physician and provided written informed consent, cerebrospinal fluid (CSF) samples were collected into three sterile tubes. These samples were then transported to the Professor Alborzi Clinical Microbiology Research Center (PACMRC), Shiraz University of Medical Sciences, Shiraz, Iran, for analysis.\u003c/p\u003e \u003cp\u003eOne CSF tube was centrifuged at 5000 \u0026times;g for 5 minutes; the pellet was subjected to Gram staining and cultured on blood and chocolate agar to identify bacterial pathogens. The second tube was used for total white blood cell (WBC) count, and based on a threshold of \u0026ge;\u0026thinsp;5 WBCs/mm\u0026sup3;, 77 samples were selected for real-time PCR to detect viral agents, including \u003cem\u003eHerpes simplex virus type 1\u003c/em\u003e and \u003cem\u003eEnterovirus.\u003c/em\u003e From the samples with WBC\u0026thinsp;\u0026lt;\u0026thinsp;5 cells/mm\u0026sup3;, 77 were randomly selected as controls and, like the case samples, underwent RT-PCR testing for viral agents (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The third CSF tube was used for biochemical analysis (protein and glucose levels). Concurrently, patient blood samples were collected for complete blood count and other parameters (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eQuantification of neuronal apoptotic bodies in CSF\u003c/h3\u003e\n\u003cp\u003eFor the semi-quantitative analysis of CD24\u0026thinsp;+\u0026thinsp;and CD54\u0026thinsp;+\u0026thinsp;apoptotic bodies, cellular debris and large particles (\u0026gt;\u0026thinsp;5000 nm) were first removed from 1 mL CSF samples by centrifugation at 250 \u0026times; g for 5 minutes. The pellet containing apoptotic bodies was re-suspended and stained extracellularly with 5 \u0026micro;l of fluorescently-labeled anti-CD24-PE and anti-CD54-PerCp antibodies (Biolegend, USA) for 20 minutes in the dark. After washing with phosphate-buffered saline (PBS), the samples were fixed and permeabilized with 200 \u0026micro;l of permeabilization buffer for 20 minutes at 4\u0026deg;C.\u003c/p\u003e \u003cp\u003eFor intracellular staining, the particles were incubated with 5 \u0026micro;l of primary antibodies against choline acetyltransferase (ChAT) and tyrosine hydroxylase (TH) (1 \u0026micro;g/mL) for 20 minutes at 4\u0026deg;C. Following a PBS wash, the samples were incubated with 5 \u0026micro;l of FITC-conjugated anti-IgG secondary antibody for 20 minutes at 4\u0026deg;C. After a final wash with PBS, the stained apoptotic bodies were resuspended and analyzed using a flow cytometer (BD FACSCalibur, USA). The complete procedures for apoptotic body isolation, staining, and the gating strategy are illustrated in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using SPSS Statistics (Version 23; IBM, Armonk, NY, USA). Categorical variables, such as gender and culture results, are presented as frequencies and were compared between groups using the Chi-square test. Continuous variables, including CSF biochemical parameters (e.g., protein, glucose), apoptotic body levels, and blood parameters (e.g., WBC, NLR, CRP, ESR), are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation or median with interquartile range, as appropriate. The Student's t-test (or Mann-Whitney U test, if normality was violated) was used to compare these continuous variables between the two study groups and to assess their association with meningitis outcomes. A p-value of \u0026lt;\u0026thinsp;0.05 was considered statistically significant. Graphs were generated using GraphPad Prism (Version 9; GraphPad Software, San Diego, CA, USA).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003ePeripheral blood and CSF parameters\u003c/h2\u003e \u003cp\u003eOne hundred and eighty four subjects were selected from 1,115 patients with suspected meningitis: 77 patients with CSF pleocytosis (WBC\u0026thinsp;\u0026ge;\u0026thinsp;5/mm\u0026sup3;) and 77 controls with normal CSF WBC counts (\u0026lt;\u0026thinsp;5/mm\u0026sup3;). The groups were well matched in terms of age and gender (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Comparative analysis of peripheral blood samples revealed that systemic inflammatory markers, including WBC, Neutrophil to lymphocyte ratio (NLR), and ESR were significantly elevated in the group with WBC\u0026thinsp;\u0026ge;\u0026thinsp;5/mm\u003csup\u003e3\u003c/sup\u003e in CSF. Analysis of CSF further showed a characteristic profile in patients, with significantly increased protein and decreased glucose concentrations compared to controls (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eBaseline characteristics and laboratory findings of patients grouped by CSF pleocytosis status (WBC\u0026thinsp;\u0026ge;\u0026thinsp;5/mm\u0026sup3; vs. \u0026lt; 5/mm\u0026sup3;). NA: Not Applicable.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eCSF (WBC)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;5\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;5\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eP\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (Y)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.3\u0026thinsp;\u0026plusmn;\u0026thinsp;23.5 y\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e20.6\u0026thinsp;\u0026plusmn;\u0026thinsp;21.5 y\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.64\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36 (47)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e37 (49)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.87\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41 (53)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e40 (51)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"6\" rowspan=\"7\"\u003e \u003cp\u003e\u003cb\u003eBlood\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWBC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10.8\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.0001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNLR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.0001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMix\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eESR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e47.3\u0026thinsp;\u0026plusmn;\u0026thinsp;35.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25.8\u0026thinsp;\u0026plusmn;\u0026thinsp;29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.02\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSugar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e110\u0026thinsp;\u0026plusmn;\u0026thinsp;36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e117\u0026thinsp;\u0026plusmn;\u0026thinsp;46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.35\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCRP\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38.3\u0026thinsp;\u0026plusmn;\u0026thinsp;49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e36\u0026thinsp;\u0026plusmn;\u0026thinsp;27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.85\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePositive BC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"7\" rowspan=\"8\"\u003e \u003cp\u003e\u003cb\u003eCSF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSugar\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46.8\u0026thinsp;\u0026plusmn;\u0026thinsp;24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e67\u0026thinsp;\u0026plusmn;\u0026thinsp;13.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.0001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eProtein\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e182\u0026thinsp;\u0026plusmn;\u0026thinsp;306\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e42\u0026thinsp;\u0026plusmn;\u0026thinsp;35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.0001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal count\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12838\u0026thinsp;\u0026plusmn;\u0026thinsp;42556\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWBC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e482\u0026thinsp;\u0026plusmn;\u0026thinsp;1286\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNLR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.7\u0026thinsp;\u0026plusmn;\u0026thinsp;9.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNA\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCD24\u0026thinsp;+\u0026thinsp;particles\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e174\u0026thinsp;\u0026plusmn;\u0026thinsp;258\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e64.5\u0026thinsp;\u0026plusmn;\u0026thinsp;73.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCD54\u0026thinsp;+\u0026thinsp;particles\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e98\u0026thinsp;\u0026plusmn;\u0026thinsp;311\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e76\u0026thinsp;\u0026plusmn;\u0026thinsp;67\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.764\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCD24+/CD54\u0026thinsp;+\u0026thinsp;particles\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e148\u0026thinsp;\u0026plusmn;\u0026thinsp;249\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e137\u0026thinsp;\u0026plusmn;\u0026thinsp;163\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.749\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eAssociation between etiologic agents, laboratory findings, and mortality\u003c/h2\u003e \u003cp\u003eBlood culture analysis revealed a significantly higher positivity rate in the pleocytosis group (10.4%, 8/77) compared to the control group (1.3%, 1/77), with an overall positivity rate of 5.8% (9/154). Of the 1,115 CSF samples cultured, 12 (1.07%) were positive. All confirmed bacterial growth was isolated from patients in the CSF-positive group, with no positive cultures detected in the control group. Analysis of CSF by molecular method to determine the viral causative agents of meningitis revealed that 18 (1.6%) CSF were positive with viral agents. Of these, eight (10.4%, 8/77) samples were in CSF positive group and 10 (13%, 10/77) samples were in the CSF negative group. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e represents the frequency of blood and CSF culture and its comparison between CSF positive and negative groups. Of the 77 positive CSF, 57 (74%) samples were negative for bacterial and viral agents therefore we defined this group as unknown cause (UC).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of bacterial and viral agents detected in blood and CSF between CSF with WBC count\u0026thinsp;\u0026lt;\u0026thinsp;5 (CSF negative) and \u0026ge;\u0026thinsp;5 cells /mm\u003csup\u003e3\u003c/sup\u003e (CSF positive). CONS: Coagulase negative staphylococci. The \u003cem\u003eP\u003c/em\u003e value indicates a significant difference in bacterial culture yields from blood and CSF between the CSF-positive and CSF-negative groups.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c2\" namest=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCSF +\u003c/p\u003e \u003cp\u003eNo (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCSF \u003csup\u003e\u0026ndash;\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eNo (%)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"2\" morerows=\"3\" nameend=\"c2\" namest=\"c1\" rowspan=\"4\"\u003e \u003cp\u003e\u003cb\u003eBlood culture\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e(154)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo growth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e145 (94)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e69 (89.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e76 (98.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e\u003cb\u003e0.001**\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eSalmonella sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eCONS\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (4.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e6 (7.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1 (1.3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eEnterococcus Sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"10\" rowspan=\"11\"\u003e \u003cp\u003e\u003cb\u003eCSF (154)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"7\" rowspan=\"8\"\u003e \u003cp\u003e\u003cb\u003eCulture\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo growth\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e140 (91)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e65 (84.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e77 (100)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\" morerows=\"7\" rowspan=\"8\"\u003e \u003cp\u003e\u003cb\u003e0.005**\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eAcinetobacter sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4 (2.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4 (5.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eBacillus sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eEnterococcus sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eCONS\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (1.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3 (3.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eProteus sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eSalmonella\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2 (2.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eS. pneumoniae\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.65)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e\u003cb\u003ePCR\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNegative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e136 (88.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e69 (89.6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e67 (87)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eHSV\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13 (8.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4 (5.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e9 (11.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eEnterovirus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5 (3.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4 (5.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1 (1.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAssessment of the association between meningitis etiology and laboratory parameters revealed no statistically significant differences in neutrophil counts, or the NLR, across bacterial, viral, and UC groups. This was despite observed trends where bacterial cases showed higher neutrophils. Additional findings indicated markedly elevated lymphocyte counts in viral meningitis CSF, contrasting with the lower glucose and higher protein levels characteristic of bacterial meningitis (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of CSF parameters between different etiologies of meningitis. \u003cem\u003eP1\u003c/em\u003e represents differences between Bacterial \u003cem\u003evs.\u003c/em\u003e Viral, \u003cem\u003eP2\u003c/em\u003e: Bacterial \u003cem\u003evs.\u003c/em\u003e unknown cause (UC), P3: Viral \u003cem\u003evs.\u003c/em\u003e UC\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCSF\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBacterial\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eViral\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eUC\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u003cem\u003eP1\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eP2\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003e\u003cem\u003eP3\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWBC (Cells/mm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e668\u0026thinsp;\u0026plusmn;\u0026thinsp;1047\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e685\u0026thinsp;\u0026plusmn;\u0026thinsp;1903\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e371.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1161\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.98\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNeutrophils (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e48.1\u0026thinsp;\u0026plusmn;\u0026thinsp;37.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e23.5\u0026thinsp;\u0026plusmn;\u0026thinsp;35.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e28.6\u0026thinsp;\u0026plusmn;\u0026thinsp;35.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.24\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.74\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLymphocytes (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e28.3\u0026thinsp;\u0026plusmn;\u0026thinsp;29.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e66.5\u0026thinsp;\u0026plusmn;\u0026thinsp;39.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e47.4\u0026thinsp;\u0026plusmn;\u0026thinsp;41.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.05\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNLR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e3.8\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e1.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e3.9\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.45\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSugar (mg/dl)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e36.3\u0026thinsp;\u0026plusmn;\u0026thinsp;25.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e55.8\u0026thinsp;\u0026plusmn;\u0026thinsp;19.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e48\u0026thinsp;\u0026plusmn;\u0026thinsp;23.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.05\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProtein (mg/dl)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e261.6\u0026thinsp;\u0026plusmn;\u0026thinsp;272\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e43.7\u0026thinsp;\u0026plusmn;\u0026thinsp;53.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e181\u0026thinsp;\u0026plusmn;\u0026thinsp;328\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u003cb\u003e0.033\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e\u003cb\u003e0.005\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAnalysis of mortality associated with meningitis etiology indicated that all fatalities were confined to the CSF-positive cohort. Specifically, bacterial meningitis accounted for 25% (n\u0026thinsp;=\u0026thinsp;2) of deaths, while the majority (75%, n\u0026thinsp;=\u0026thinsp;6) were of unknown origin (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eAssociation between CSF neuronal apoptotic body levels and patient clinical outcomes\u003c/h3\u003e\n\u003cp\u003eAnalysis of neuronal apoptotic bodies based on WBC count revealed that CSF samples with \u0026ge;\u0026thinsp;5 cells/mm\u0026sup3; had significantly higher frequencies of ChAT+/TH\u0026thinsp;+\u0026thinsp;CD24\u0026thinsp;+\u0026thinsp;apoptotic bodies. In contrast, the frequencies of ChAT+/TH\u0026thinsp;+\u0026thinsp;CD54\u0026thinsp;+\u0026thinsp;and ChAT+/TH\u0026thinsp;+\u0026thinsp;CD24\u0026thinsp;+\u0026thinsp;CD54\u0026thinsp;+\u0026thinsp;particles showed no significant difference between the high and low WBC groups. Evaluation of apoptotic body frequency in the CSF showed no statistically significant association with the etiology of meningitis (bacterial, viral, or unknown), as detailed in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. In addition, no significant differences were observed in the frequency of neuronal apoptotic bodies when compared across the different bacterial and viral etiologies of meningitis (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparing the levels of apoptotic body in the CSF with different characteristics. \u003cem\u003eP1\u003c/em\u003e: CSF with WBC\u0026thinsp;\u0026ge;\u0026thinsp;5 \u003cem\u003evs\u003c/em\u003e. WBC\u0026thinsp;\u0026lt;\u0026thinsp;5, \u003cem\u003eP2\u003c/em\u003e: Bacterial \u003cem\u003evs.\u003c/em\u003e viral meningitis, \u003cem\u003eP3\u003c/em\u003e: Bacterial \u003cem\u003evs.\u003c/em\u003e unknown cause of meningitis, \u003cem\u003eP4\u003c/em\u003e: Viral \u003cem\u003evs.\u003c/em\u003e unknown cause of meningitis, \u003cem\u003eP5\u003c/em\u003e: Survivors \u003cem\u003evs.\u003c/em\u003e non-survivors.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCD24+\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eCD54+\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCD24\u0026thinsp;+\u0026thinsp;CD54+\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"6\" rowspan=\"7\"\u003e \u003cp\u003e\u003cb\u003eCSF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWBC\u0026thinsp;\u0026ge;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e174\u0026thinsp;\u0026plusmn;\u0026thinsp;258\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e98\u0026thinsp;\u0026plusmn;\u0026thinsp;311\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e148\u0026thinsp;\u0026plusmn;\u0026thinsp;284\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eWBC\u0026thinsp;\u0026lt;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e64\u0026thinsp;\u0026plusmn;\u0026thinsp;73\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e86\u0026thinsp;\u0026plusmn;\u0026thinsp;66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e137\u0026thinsp;\u0026plusmn;\u0026thinsp;162\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eBacterial\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e104\u0026thinsp;\u0026plusmn;\u0026thinsp;113\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e94\u0026thinsp;\u0026plusmn;\u0026thinsp;127\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e197\u0026thinsp;\u0026plusmn;\u0026thinsp;321\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eViral\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e86\u0026thinsp;\u0026plusmn;\u0026thinsp;127\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e79\u0026thinsp;\u0026plusmn;\u0026thinsp;72\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e119\u0026thinsp;\u0026plusmn;\u0026thinsp;81\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e186\u0026thinsp;\u0026plusmn;\u0026thinsp;287\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e103\u0026thinsp;\u0026plusmn;\u0026thinsp;353\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e138\u0026thinsp;\u0026plusmn;\u0026thinsp;287\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSurvivor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e112\u0026thinsp;\u0026plusmn;\u0026thinsp;201\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e94\u0026thinsp;\u0026plusmn;\u0026thinsp;230\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e145\u0026thinsp;\u0026plusmn;\u0026thinsp;236\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNon-survivor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e105\u0026thinsp;\u0026plusmn;\u0026thinsp;86\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63\u0026thinsp;\u0026plusmn;\u0026thinsp;40\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e99\u0026thinsp;\u0026plusmn;\u0026thinsp;92\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eP1\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cb\u003e0.0001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eP2\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eP3\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eP4\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.17\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eP5\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eApoptotic body levels in CSF by infectious cause. DM; Diagnostic method, CONS; Coagulase Negative \u003cem\u003eStaphylococci, HSV; Herpes simplex virus\u003c/em\u003e\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDM\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCause\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNo.\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCD24+\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eCD54+\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eCD24\u0026thinsp;+\u0026thinsp;CD54+\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"8\" rowspan=\"9\"\u003e \u003cp\u003e\u003cb\u003eCSF\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"6\" rowspan=\"7\"\u003e \u003cp\u003e\u003cb\u003eCulture\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eAcinetobacter sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e69\u0026thinsp;\u0026plusmn;\u0026thinsp;16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e72\u0026thinsp;\u0026plusmn;\u0026thinsp;18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e93\u0026thinsp;\u0026plusmn;\u0026thinsp;79\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eBacillus sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e31\u0026thinsp;\u0026plusmn;\u0026thinsp;19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e57\u0026thinsp;\u0026plusmn;\u0026thinsp;30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e106\u0026thinsp;\u0026plusmn;\u0026thinsp;97\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eEnterococcus sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e235\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e281\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eCONS\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e145\u0026thinsp;\u0026plusmn;\u0026thinsp;125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e39\u0026thinsp;\u0026plusmn;\u0026thinsp;28\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e222\u0026thinsp;\u0026plusmn;\u0026thinsp;338\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eProteus sp.\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e378\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e131\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1161\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eSalmonella\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e17.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e46.5\u0026thinsp;\u0026plusmn;\u0026thinsp;48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e19\u0026thinsp;\u0026plusmn;\u0026thinsp;7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eS. pneumoniae\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e28.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e520\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e37\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003ePCR\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eHSV\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e87\u0026thinsp;\u0026plusmn;\u0026thinsp;118\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e93\u0026thinsp;\u0026plusmn;\u0026thinsp;77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e127\u0026thinsp;\u0026plusmn;\u0026thinsp;71\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eEnterovirus\u003c/em\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e112\u0026thinsp;\u0026plusmn;\u0026thinsp;167\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e35\u0026thinsp;\u0026plusmn;\u0026thinsp;18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e131\u0026thinsp;\u0026plusmn;\u0026thinsp;133\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eEvaluation of the association between apoptotic body frequency and patient outcome showed that the levels of ChAT/TH\u0026thinsp;+\u0026thinsp;CD24+, CD54+, and CD24\u0026thinsp;+\u0026thinsp;CD54\u0026thinsp;+\u0026thinsp;particles were not significantly different between survivors and non-survivors, although they were numerically higher in survivors (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eDifferentiating bacterial meningitis from viral meningitis is one of the main challenges for physicians in order to prescribe the most effective medication at the right time. Nevertheless, despite all the efforts made, in cases where bacterial culture and molecular methods fail to identify the causative agents of meningitis, and laboratory findings yield inconclusive results, differential diagnosis remains uncertain and ambiguous. Considering that previous research has demonstrated greater tissue damage in bacterial meningitis compared to the viral form, often leading to more serious complications [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e], this study aimed to assess the frequency of ChAT/TH\u0026thinsp;+\u0026thinsp;particles expressing CD24 and CD54 molecules (reflecting neuronal and immune cell markers released during the progression of meningitis) in CSF of patients meningitis with different etiologies.\u003c/p\u003e \u003cp\u003eRegarding the CSF analysis, WBC count showed that bacterial growth was substantially more frequent in the CSF-positive (WBC\u0026thinsp;\u0026ge;\u0026thinsp;5cells/mm\u003csup\u003e3\u003c/sup\u003e) group, indicating a significant association between elevated WBC counts and bacterial infection. In contrast, viral infection showed no such association, while the results for meningitis with unknown cause (UC) fell between those of bacterial and viral forms. Furthermore, CSF protein and sugar were significantly different in CSF-positive group compared with those in CSF-negative group (WBC\u0026thinsp;\u0026lt;\u0026thinsp;5cells/mm\u003csup\u003e3\u003c/sup\u003e). A comparison of WBC subpopulations, including neutrophils, lymphocytes, and the neutrophil-to-lymphocyte ratio (NLR), across meningitis cases with different etiologies (bacterial, viral and UC) revealed no statistically significant differences between the study groups. Nonetheless, subtle trends were noted in which bacterial meningitis cases tended to show higher neutrophil counts, while viral meningitis cases exhibited relatively elevated lymphocyte levels. In a previous study with a substantial infant sample size, neutrophil predominance in CSF showed the strongest association with the diagnosis of bacterial meningitis [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Another study on neonates and infants aged 1\u0026ndash;3 month reported that a cerebrospinal fluid (CSF) neutrophil count of 2\u0026times;10⁶/L or higher was independently associated with a higher probability of bacterial meningitis, with positive likelihood ratios of at least 5 and 3, respectively [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eCluster of differentiation 24 (CD24) is a small, heavily glycosylated adhesion protein expressed on immune, epithelial, neural, and muscle cells [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Furthermore, this molecule highly expressed on immature T cells, but its expression declines upon maturation. However, following T cell activation, CD24 is rapidly upregulated and plays a critical role in promoting optimal activation and survival of certain T cell subsets in peripheral lymphoid organs and the central nervous system [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. This cell surface protein (CD24) interacts with multiple receptors, including P-selectin, Siglec-10, and β1 integrin. Through its engagement with these receptors and its association with the Notch signaling pathway, CD24 regulates key cellular processes such as adhesion, migration, differentiation, and apoptosis [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Analysis of CD24\u0026thinsp;+\u0026thinsp;particles in CSF demonstrated significantly higher frequencies in bacterial meningitis and unspecified meningitis compared to negative CSF controls [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Although CD24\u0026thinsp;+\u0026thinsp;particle levels were more frequent in bacterial meningitis compared to viral meningitis, the difference was not statistically significant, indicating that CD24 lacks sufficient discriminatory power to differentiate between these etiologies. Furthermore, CD24 levels showed no significant association with clinical outcomes (survival vs. non-survival) in meningitis patients.\u003c/p\u003e \u003cp\u003eThe CD54 molecule, also known as intercellular adhesion molecule 1 (ICAM-1), is constitutively expressed on neurons [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] and endothelial cells at low levels and can be induced on antigen-presenting cells, T cells, and B cells upon stimulation. It plays a crucial role in leukocyte adhesion and immune activation. ICAM-1 binds to the β2 integrin lymphocyte function-associated antigen 1 (LFA-1; CD11a/CD18), a key interaction that facilitates immune cell migration and triggers inflammatory responses [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Based on its role in the immune responses, we compared the concentration of particles expressing CD54 in CSF between bacterial and viral meningitis groups. CD54 levels were not significantly different between the bacterial and viral meningitis groups, despite an observed increase in the bacterial group. Importantly, both meningitis groups (bacterial and viral) exhibited significantly higher CD54 levels compared to the negative controls. Furthermore, CD54 level was not significantly different between survivors and non-survivors patients. Given the observed increase of leukocytes in the CNS during meningitis, the upregulation of CD54\u0026thinsp;+\u0026thinsp;particles may result from apoptosis induced in brain endothelial cells and leukocytes combating pathogens. A recent study focused on brain microenvironment endothelial cells revealed a key defense mechanism against meningitis. It showed that caspase-8 mediated apoptosis helps recruit neutrophils, which are essential for pathogen clearance [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Therefore, it seems that apoptosis can be useful in the infiltration of leukocytes and activation and contraction of immune responses and consequently meningitis regression. However, CD54 and CD24 expressing particles in our study were not significantly different between bacterial and viral induced meningitis. While bacterial interaction with neurons causes neuroinflammation and neuronal death [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e], we found no significant difference in the presence of neuronal enzymes (ChAT and TH) [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e, \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e], on CD24/CD54-expressing particles between bacterial and viral meningitis cases. Given that, neuronal damage is the major consequence of bacterial and in less extent viral meningitis, it seems that the levels of CD24\u0026thinsp;+\u0026thinsp;and CD54\u0026thinsp;+\u0026thinsp;particles expressing TH and CHAT be more frequent in bacterial compared to viral meningitis. However, no significant difference was observed between the two study groups or between survivors and non-survivors. The limited number of bacterial and viral positive samples, a key limitation of the study, likely accounts for this discrepancy.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAlthough apoptosis is a major outcome of bacterial and viral meningitis, we observed no significant difference in CD24/CD54\u0026thinsp;+\u0026thinsp;TH/CHAT\u0026thinsp;+\u0026thinsp;particle levels between the bacterial and viral groups, or between survivors and non-survivors. However, a substantial increase was observed in CSF-positive samples (WBC\u0026thinsp;\u0026ge;\u0026thinsp;5 cells/\u0026micro;L) compared to CSF-negative samples (WBC\u0026thinsp;\u0026lt;\u0026thinsp;5 cells/\u0026micro;L). This suggests that the elevated particle levels are likely a consequence of leukocyte recruitment into the CNS and subsequent neuronal apoptosis, rather than a specific response to the type of pathogens or patient survival.\u003c/p\u003e"},{"header":"Declarations","content":" \u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003e This study was approved by the Ethics Committee of the National Institute for Medical Research and Development (NIMAD) with the code IR.NIMAD.REC.1397.096. All procedures were performed in accordance with the relevant guidelines and regulations.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eCompeting interests\u003c/strong\u003e \u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eClinical trial number\u003c/h2\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFundings\u003c/h2\u003e \u003cp\u003eThis work was supported by the NIMAD under grant number 971220 and by PACMRC under grant number 97\u0026thinsp;\u0026minus;\u0026thinsp;2.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eS.F. and S.S.H. contributed equally to this work. Me.K. conceived and designed the study. S.F., S.S.H., M.C., Ma.K., and Z.J. were responsible for data collection and investigation. M.C. and Me.K. performed the laboratory experiments and flow cytometry. S.F. and S.S.H. conducted data analysis. Me.K. supervised the project and acquired funding. The manuscript was drafted by S.F., S.S.H., and Z.J. and critically reviewed and edited by all authors. All authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e \u003cp\u003eWe extend our sincere gratitude to the National Institute for Medical Research and Development (NIMAD) and the Professor Alborzi Clinical Microbiology Research Center (PACMRC) for their generous support of this study.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eAli M, Chang BA, Johnson KW, Morris SKJV. 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Microorganisms 2021, 9(3).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLamb AE, Rent S, Brannon AJ, Greer JL, Ndey-Bongo NP, Cho SH, Greenberg RG, Benjamin DK Jr., Clark RH, Kumar KR. Diagnostic Utility of Cerebrospinal Fluid White Blood Cell Components for the Identification of Bacterial Meningitis in Infants. J Pediatr Infect Dis Soc. 2023;12(Supplement2):S44\u0026ndash;52.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eO'Leary C, Pittet LF, Beaumont R, Constable L, Daley A, Hodge I, Jacobs SE, King A, Tan C. Curtis NJAoDiC: Predictive performance of cerebrospinal fluid parameters for diagnosis of meningitis in infants: a cohort study. 2025, 110(3):209\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFang X, Zheng P, Tang J, Liu YJC. immunology m: CD24: from A to Z. 2010, 7(2):100\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhang X, Yu C, Liu J-Q, Bai X-FJF. Dendritic cell expression of CD24 contributes to optimal priming of T lymphocytes in lymph nodes. 2023, 14:1116749.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWei M, Wang PGJPMB, Science T. Desialylation in physiological and pathological processes: New target for diagnostic and therapeutic development. 2019, 162:25\u0026ndash;57.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKedarinath K, Fox CR, Crowgey E, Mazar J, Phelan P, Westmoreland TJ, Alexander KA, Parks GDJV. CD24 expression dampens the basal antiviral state in human neuroblastoma cells and enhances permissivity to zika virus infection. 2022, 14(8):1735.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu Z, Huang Y, Cao B-B, Qiu Y-H, Peng Y-P. Th17 cells induce dopaminergic neuronal death via LFA-1/ICAM-1 interaction in a mouse model of Parkinson\u0026rsquo;s disease. Mol Neurobiol. 2017;54(10):7762\u0026ndash;76.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSingh V, Kaur R, Kumari P, Pasricha C, Singh R. ICAM-1 and VCAM-1: Gatekeepers in various inflammatory and cardiovascular disorders. Clin Chim Acta. 2023;548:117487.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGuerra-Espinosa C, Jim\u0026eacute;nez-Fern\u0026aacute;ndez M, S\u0026aacute;nchez-Madrid F, Serrador JM. ICAMs in immunity, intercellular adhesion and communication. Cells. 2024;13(4):339.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang X, Lin W, Ye L, Chen X, Ren J, Xue F, Dai J, Tang FJMR. Caspase-8 drove apoptosis of BMECs to promote neutrophil infiltration and DE205B clearance in meningitis. 2025:128223.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIovino F, Seinen J, van Henriques-Normark B. Dijl JMJTiM: How does Streptococcus pneumoniae invade the brain? 2016, 24(4):307\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAschrafi A, Gioio AE, Dong L, Kaplan BBJE. Disruption of the axonal trafficking of tyrosine hydroxylase mRNA impairs catecholamine biosynthesis in the axons of sympathetic neurons. 2017, 4(3).\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGranger AJ, Wang W, Robertson K, El-Rifai M, Zanello AF, Bistrong K, Saunders A, Chow BW, Nu\u0026ntilde;ez V. Turrero Garc\u0026iacute;a MJE: Cortical ChAT\u0026thinsp;+\u0026thinsp;neurons co-transmit acetylcholine and GABA in a target-and brain-region-specific manner. 2020, 9:e57749.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-infectious-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"infd","sideBox":"Learn more about [BMC Infectious Diseases](http://bmcinfectdis.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/infd","title":"BMC Infectious Diseases","twitterHandle":"#bmcinfectdis","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Meningitis, Differential diagnosis, Biomarkers, Apoptosis","lastPublishedDoi":"10.21203/rs.3.rs-8095123/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8095123/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eIntroduction:\u003c/h2\u003e \u003cp\u003eRapid and accurate differentiation of bacterial and viral meningitis is critical for effective treatment but remains challenging. To address this, our study investigated the frequency of apoptotic bodies in cerebrospinal fluid (CSF) as a potential diagnostic biomarker to distinguish the cause of infection.\u003c/p\u003e\u003ch2\u003eMaterials and Methods\u003c/h2\u003e \u003cp\u003eThe study was conducted on 1115 CSF samples collected from patients clinically suspicious of meningitis. CSF was directly analyzed to evaluate leukocyte count, protein, and sugar concentration, and to determine bacterial causative agents using direct smear, Gram staining, and culture on blood and chocolate agar. Furthermore, to determine viral meningitis, PCR was used to detect the presence of viral agents such as \u003cem\u003eHerpes simplex virus type 1\u003c/em\u003e (HSV-1) and \u003cem\u003eEnterovirus\u003c/em\u003e (EV). Given the leukocyte count, the samples were divided into CSF with less or more than 5 leukocytes per ml as negative and positive CSF, respectively. Then CSF was assessed for the frequency of small particles as neuronal apoptotic bodies stained with fluorochrome-labeled anti-CD24 and CD54 antibodies and intracellular staining of Choline acetyltransferase (ChAT) and Tyrosine hydroxylase (TH) using flow cytometry.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOut of 1,115 analyzed CSF samples, 77 were positive (WBC\u0026thinsp;\u0026ge;\u0026thinsp;5/mm\u0026sup3;), and 77 negative samples (WBC\u0026thinsp;\u0026lt;\u0026thinsp;5/mm\u0026sup3;) were randomly selected as controls. Within the positive group, the causes of infection were identified as bacterial for 10 samples, viral for 12, and the cause remained unknown for 55 samples. No significant differences were observed in the levels of CD24+, CD54+, or CD24/CD54\u0026thinsp;+\u0026thinsp;apoptotic bodies\u0026mdash;which express the neuronal markers ChAT and TH\u0026mdash;across the bacterial, viral, and unknown cause (UC) infection groups. Despite this, their frequencies were substantially elevated in all positive CSF samples compared to negative controls.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eWhile the levels of apoptotic bodies in CSF can differentiate between samples with pleocytosis (WBC\u0026thinsp;\u0026ge;\u0026thinsp;5/mm\u0026sup3;) and those without, they cannot distinguish bacterial from viral meningitis. This suggests that the elevation in neuronal particles is likely a nonspecific consequence of leukocyte recruitment into the CNS and subsequent neuronal apoptosis, rather than a pathogen-specific response or a marker of patient survival. Furthermore, the low incidence of confirmed bacterial and viral meningitis in our study may have influenced these results.\u003c/p\u003e","manuscriptTitle":"Predictive Value of Neuronal Apoptotic Bodies in Cerebrospinal Fluid for the Differential Diagnosis of Bacterial from Viral Meningitis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-22 09:07:00","doi":"10.21203/rs.3.rs-8095123/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-02T17:31:37+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-05T19:29:13+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-12-27T14:04:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"49938191533535491645497382055452327081","date":"2025-12-21T12:17:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"308647329370632707016969810971701591212","date":"2025-12-19T17:30:48+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-12T08:55:52+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-11-14T19:51:46+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-14T10:30:24+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-11-14T10:27:21+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Infectious Diseases","date":"2025-11-12T10:14:21+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-infectious-diseases","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"infd","sideBox":"Learn more about [BMC Infectious Diseases](http://bmcinfectdis.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/infd","title":"BMC Infectious Diseases","twitterHandle":"#bmcinfectdis","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"2fb4962d-55ee-4d51-a6af-f78861453481","owner":[],"postedDate":"December 22nd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-02-02T17:39:45+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-22 09:07:00","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8095123","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8095123","identity":"rs-8095123","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}