Clinical characteristics of children hospitalized with Chlamydia pneumoniae pneumonia

Clinical characteristics of children hospitalized with Chlamydia pneumoniae pneumonia | 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 Clinical characteristics of children hospitalized with Chlamydia pneumoniae pneumonia Min Wu, Luting Zhou, Yeming Chen, Shun Wang, Ying Sun, Zhiqing Liu, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7333387/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: Chlamydia pneumoniae is an atypical respiratory pathogen that contributes to community-acquired pneumonia in children. However,the clinical manifestations are often non-specific, posing challenges for early identification. The purpose of this study is to summarize the Clinical characteristics of Chlamydia pneumoniae pneumonia in children,thereby facilitating its recognition prior to the availability of pathogen detection results. Methods: Children hospitalized with community-acquired pneumonia between January 1, 2023 to April 30, 2025 in the Department of Respiratory Medicine,Children’s Hospital of Soochow University were enrolled. Nasopharyngeal aspirates or BALF were collected for respiratory pathogen detection and medical records of C. pneumoniae infection were retrospectively collected. Results: Of 15144 hospitalized children with community-acquired pneumonia, 260(1.71%,260/15144) had C. pneumoniae infection.After exclusions criteria, 226 cases with complete data were analyzed.Among the 226 children,the male-to-female ratio was 2:1 with a median age of 11.2 (9.5-13.0)years.Of which,206 (91.15%) patients were aged between 6–15 years old .The average length of hospital stay was 6.54±1.59 days.The most common symptoms were cough (100%), yellow sputum (42.60%),fever (39.38%).The median duration from onset to admission was 7(5.0,10.0)days and median pre-admission fever durations of 5.0(3.0,7.0)days. Radiological examination showed that 95.13% had pulmonary parenchymal changes; 9.64% had unilateral involvement.,mostly in the right lower lobe (31.85%)and 49 left lower lobes(21.68%). Lesions in ≥2 lobes occurred in 6.64% Complications included atelectasis（3.98%）,pleural effusion（3.54%）,and bronchiectasia（1.33%）. All cases were treated with azithromycin or doxycycline，51 cases (22.56%)received fiberoptic bronchoscopy and lavage treatment,with full recovery and no severe outcomes. Conclusion: The detection of C. pneumoniae in children has an increasing trend.C. pneumoniae pneumonia mainly occurs in 6–15-years, characterized by cough, yellow sputum, fever, unilateral lower-lobe parenchymal changes on imaging. Inflammatory markers are normal, complications rare. Macrolides/doxycycline work well with good outcomes. Chlamydia pneumoniae Pneumonia Chidren Clinical characteristics Figures Figure 1 Background C.pneumoniae is an atypial respiratory pathogen associated with community-acquired pneumonia,exhibiting periodic epidemic patterns [1] . As a strictly intracellularly parasitic prokaryote, it can persist in a carrier state or cause chronic infections [2] .Besides respiratory infections, C. pneumoniae has been linked to various chronic diseases such as atherosclerosis, Alzheimer's disease,asthma and chronic obstructive pulmonary disease [3-6] . According to previous literatures,respiratory infections caused by C.pneumoniae typically exhibit a low incidence rate (0.17%~16.2%) [7-10] and relatively mild clinical manifestations.Approximately 60-80% of C. pneumoniae infections is asymptomatic state and such infections tend to progress to a chronic or asymptomatic state [11] .However,pulmonary imaging findings in C.pneumoniae pneumonia predominantly shows subpleural mass-like high-density shadows , which are prone to misdiagnosis as mycoplasma pneumonia,fungal pneumonia, tubercolous pneumonia, pulmonary embolism and other conditions. Owing to variations in detection methodologies, the incidence of C. pneumoniae infection exhibits significant variability.Additionally,the lack of effective C. pneumoniae detection methods in some medical institutions further contributes to missed diagnoses and misdiagnoses.Several studies [10,12-13 ]have reported a rising prevalence of C. pneumoniae in recent years. Accordingly, this study aims to analyze its clinical features to provide references for early diagnosis and treatment. METHODS Patients In this study,the chidren hospitalized with community-acquired pneumonia in Department of Respiratory Medicine,Children’s Hospital of Soochow University, between January 1, 2023 to April 30, 2025 were enrolled.We then retrospectively analyzed the clinical data of those children diagnosed with C.pneumoniae infection. The exclusion criteria for this study were as follows: (1) patients with incomplete clinical data; (2) patients with hereditary metabolic diseases, neurological disorders, congenital heart disease, and/or immunodeficiency. Detection of respiratory pathogens analysis Polymerase chain reaction(PCR) was used to detect 13 tpyes of respiratory pathogens ,including respiratory syncytial virus infection (RSV), human metapneumovirus (HMPV), human bocavirus (HBoV), and human rhinovirus (HRV),influenza virus A (FluA), influenza virus B (Flu B), parainfluenza virus I-III(PIV I, PIV II, PIV III), adenovirus (ADV), and MP in Nasopharyngeal aspirate or bronchoalveolar lavage fluid (BALF) [ 14 ] . Bacterial dentification was performed using quantitative analysis by inoculating Nasopharyngeal aspirate or BALF samples onto selected media and incubated for 18–24 h. Bacterial growth exceeding 10 3 colony-forming units/mL was regarded as clinically significant [ 15 ] . Statistical analyses Data processing was conducted using SPSS 26.0statistical software(IBM, SPSS, Chicago, IL, USA).Measurement data that did not conform to a normal distribution, they were expressed as M(P 25 , P 75 ),the inter-group comparisons were conducted using the rank sum test.The enumeration data was presented as counts or percentage. P<0.05 was considered statistically significant. RESULTS Demographics characteristics and clinical symptoms In this study,a total of 15144 hospitalized children with community-acquired pneumonia were included,260(1.71%,260/15144) had C. pneumoniae infection.The The detectable rate of C. pneumoniae were 4.24% in 2023,26.52% in 2024 and 34,89%between January,1 to April, 30,2025.Both the number of detected cases and detection rate of C. pneumoniae in this study showed an obvious upward trend since 2023.Table 1 , Fig. 1 . After applying the exclusions criteria, 226 cases with complete data were enrolled for analysis.Among the 226 patients,153 (67.70%) were male and 73 (32.30%) were female,the male-to-female ratio was 2:1. The average length of hospital stay was 6.54 ± 1.59 days.The age of patients ranged from 3 years to 18 years.5 patients (2.21%)were aged ≤ 6years, 206 (91.15%) patients were aged between 6–15 years,and15(6.63%)patients were aged ≥ 15 years.The median age was 11.2 (9.5, 13.0)years.Table 2 . The most common clinical symptoms were cough (100%, 226/226), fever (39.38%, 89/226), and chest pain(3.98%, 9/226),wheeze(2.21%, 5/226),tachypnea (0.44%, 1/226). Among the 89 feverish patients,28 (12.39%) had low fever(T<38℃),40(17.70%) had moderate fever(38 ≤ T<39℃), and 21 (9.29%) had high fever(T ≥ 39℃).The median duration of fever before admission was 5.0(3.0, 7.0)days.Table 2 . The duration of coughing before admission ranged from 1-30days.The median duration was 7(5.0–10.0)days.The symptom of cough included dry cough(13.71%,31/226) and wet cough(86.28%,195/226)).95 (42.60%, 95/226) could expectorate yellow sputum.No patients presented with cyanosis or dyspnea.Upon lung auscultation, 136 cases (60.17%, 136/226) showed no rales, 69 cases (30.53%, 69/226) had moist rales, and only 5 cases had wheezing.Table 2 . Table 1 Detection of C. pneumoniae between January, 2023 to April, 2025 month 2023 2024 2025 inpatients detected cases Detection rate inpatients detected cases Detection rate inpatients detected cases Detection rate 1 371 3 0.81 573 2 0.35 460 25 5.43 2 400 2 0.50 543 1 0.18 412 40 9.70 3 721 6 0.83 535 1 0.18 403 20 4.96 4 678 4 0.59 449 6 1.33 410 61 14.8 5 666 4 0.60 428 10 2.33 6 645 5 0.77 452 9 1.99 7 692 0 0.00 524 5 0.95 8 692 1 0.14 459 9 1.96 9 658 0 0.00 440 8 1.81 10 712 0 0.00 466 16 3.43 11 678 0 0.00 469 4 8.52 12 693 0 0.00 515 18 3.49 Table 2 clinical characteristics of C.pneumoniae pneumonia Patient characteristics Case N(%) Sex (male/female) 153/73 median age(years) 11.2(9.5–13.0) hospital stays(days) 6.54 ± 1.59 The duration of coughing before admission(days) 7(5.0, 10.0) The duration of fever before admission(days) 5(3.0, 7.0) Age group ≤6years 5(2.21) 6-15years 206(91.15) ≥ 15years 15(6.63) cough 226(100) dry cough 31(13.71) Wet cough 195(86.28) white sputum 17(7.52) Yellow sputum 95(42.60) Cannot cough up phlegm 83(36.72) fever 89(39.38) low fever(T<38℃) 28(12.39) moderate fever(38℃≤T<39℃) 40(17.70) high fever(T ≥ 39℃) 21(9.29) chest pain 9(3.98) wheeze 5(2.21) polypnea 1(0.44) cyanosis 0(0) dyspnea 0(0) Pulmonary signs moist rales 69(30.53) Wheezing rales 5(2.21) moist and Wheezing rales 11(4.86) absence signs 136(60.17) Imaging features Among the 226 patients with Chlamydia pneumoniae pneumonia,180 (79.64%,180/226)cases had unilateral lung involvement.The lesion most commonly occurred in the lower lobes of the lungs,31.85% (72//226) in the right lower lobe and 21.68% (49/226) in the left lower lobe; 6.64% (15/226) of the patients had lesions involving more than two lung lobes. Imaging examination revealed that 92.92% (210/226) of the patients had massive high-density shadows.Pulmonary complications of Chlamydial pneumoniae pneumonia identified by imaging include 9(3.98%, 9/226)cases of atelectasis,8༈3.54%, 8/226༉cases of pleural effusion,3༈1.33%, 3/226༉case of bronchiectasia.Table 3 . Table 3 Imaging features of C.pneumoniae pneumonia chest imaging Case N(%) Site of pneumonia Right lung 109(48.23) superior lobe of right lung 18(7.96) middle lobe of right lung 12(5.31) inferior lobe of right lung 72(31.85) middle lob、inferior lobe of right lung 7(3.09) Left lung 71(31.42) superior lobe of left lung 14(6.20) inferior lobe of left lung 49(21.68) superior lobe、inferior lobe of left lung 8(3.54) both lungs 46(20.35) pulmonary complications Pulmonary atrophy 9(3.98) pleural effusion 8(3.54) bronchiectasia 3(1.33) pulmonary embolism 0(0) lung necrosis 0(0) laboratory examination results The white blood cell count was 9.6 (7.8, 11.3) × 10 9 /L, with a neutrophil proportion of 62.3% (57%, 68%). A total of 70.83% of patients had an elevated platelet count (greater than 300 ×10 9 /L), with a median of 320(270, 382༉× 10 9 /L.84 (37.16%,) cases had elevated blood C-reactive protein, with a median of 6.5mg/dl༈2.7, 17.5༉. Additionally, 69(30.53%) cases had elevated LDH levels.90(39.82%)cases had elevated D-dimer levels.Indicators related to humoral immunity and cellular immunity were generally within normal ranges.Table 4 . Table 4 laboratory examination results of Chlamydia pneumoniae pneumonia laboratory examination Case N(%) WBC count 9.6(7.8, 11.3) 10×109 /L 98(53.36) N% 62.3(57, 68) 70% 45(19.91) CRP(mg/l) 6.5(2.7, 17.5) ≥ 8mg/l 84(37.16) <8mg/l 142(62.83) PLT 320(270, 382) 300×109 /L 153(70.83) LDH(U/L) 262(228, 309) ≤ 295U/L 151(66.81) > 295U/L 69(30.53) D-dimer(ug/L) 410(297, 592) ≤ 500U/L 136(60.18) > 500U/L 90(39.82) APTT(s) 39.7(36.3, 43.8) FDP(ug/L) 2330(1590, 2330) CD3CD4(%) 33.06 ± 9.36 CD3CD8(%) 28.73 ± 8.53 CD19(%) 17.01 ± 7.01 CD16CD56(%) 12.16 ± 6.98 CD19CD23(%) 9.60 ± 4.74 LgA 1.8 ± 0.77 lgG 12.7 ± 3.40 lgM 1.63(1.28, 2.09) Detection of co-infection A total of 93(35.50%) cases were detected with co-infections. The most commonly identified pathogens were viruses (27.87%). Among the detected viruses, HRV (20.8%)was the most common, followed by ADV (3.10%,7/226). Mixed bacterial infections were detected in 21 case, including Streptococcus pneumoniae(5.31%)、Moraxella catarrhalis(2.21%) and Haemophilus influenzae(1.77%).Table 5 , Table 5 The co-infection pathogen of Chlamydia pneumoniae pneumonia pathogen Case N(%) virus 63(27.87) HRV 47(20.80) ADV 7(3.10) hMPV 3(1.33) PIV 2(0.88) Flu 2(0.88) RSV 1(0.44) HBoV 1(0.44) MP 0(0) bacteria 21(9.29) Streptococcus pneumoniae 12(5.31) Moraxella catarrhalis 5(2.21) Haemophilus influenzae 4(1.77) Bronchoscopy and BALF collection Among the 226 patients, 51 (22.56%) underwent flexible bronchoscopy and bronchoalveolar lavage .All 51 cases tested positive for Chlamydia nucleic acid in BALF.The primary finding under bronchoscopy was a large amount of white fluffy exudate (19.91%,45/226) in the affected lung lobes, and sputum plugs observed in 2 cases. Treatment All children with C.pneumoniae Pneumonia received treatment with azithromycin or doxycycline. Glucocorticoid therapy was administered to 123(54%)cases due to the slow improvement of the cough symptoms and delayed absorption of the lung lesions. All the patients were followed up for 2 months after discharge.Symptoms resolved completely with lesions absorption confirmed by imaging.No respiratory support, intensive care admission or deaths occurred. DISCUSSION The overall prevalence rate of C.pneumoniae pneumonia in children and adults was 3.5% (95% CI 2.2% − 4.9%) [ 16 ] .The detection rate in the present study was 1.71%, which was higher than the 0.34% reported in Beijing 2015–2019 [ 17 ] but lower than the 6.5% reported in a Japanese study [ 18 ] .This discrepancy may be attributed to the fact that C.pneumoniae diagosis in our study was based on real-time PCR,whereas the Japanese study employed three distinct detection methods.Additionally, the Japanese study had a limited sample size of clinical data(232 cases) and included adults populations. In the present study,the detection rate of C. pneumoniae exhibited an upward trend starting from 2023,with an approximate 6-fold increase in 2024.This trend is consistent with previous studies [ 10 ] [ 12 ] .In Marseille,Sophie Edouard reported a 19-fold increase of Chlamydia pneumoniae diagnoses in 2024 and he acquired four C.pneumoniae genomes, all belonging to serotype ST16. The increased detection rate of C.pneumoniae may be related to multiple factors. First, Chlamydia pneumoniae infection exhibits periodic epidemic pattern with geographical variations in cycle durations,approximately 4–6 year cycles [ 1 ] .Starting from October 2024, especially since 2025,the detection incidence of C.pneumoniae has significantly increased,indicating that C.pneumoniae is entering its epidemic peak again.Second, following the COVID-19 pandemic, children's respiratory immunity has been impacted by the successive prevalence of the RSV,MP and influenza virus ,leading to increased susceptibility to subsequent C.pneumoniae infection.Additionally,the popularization of molecular diagnostic techniques has played a role: multiplex PCR have been widely adopted, markedly improving the detection rate of asymptomatic or mild infections. In the present study,children with C. pneumoniae pneumonia predominantly affect those aged 6–15 years, with a median age of 11.2 years. The study [ 17 ] reported in China showed that the highest incidence was in 10–14 years old while in France was between 10–15 years [ 12 ] .Therefore, C.pneumoniae pneumonia mainly occurs in older children. The main symptoms included cough ,yellow sputum and fever, chest pain and wheezing were relatively rare,only one case presented with hemoptysis.Inflammatory markers such as blood cell count,C-reactive protein,LDH,D-dimer were mostly normal ranges, similar to previous reports [ 10 , 18 ] .Chest imaging findings predominantly present with unilateral pulmonary involvement and mass-like high-density opacities.In contrast,Wen [ 19 ] reported 10 cases of C.pneumoniae pneumonia ,4 cases manifested with chest pain.They identified that the common chest imaging findings was a subpleural highdensity mass-like shadow with a halo sign,which may account for the occurrence of chest pain. In this study,35.50% of the C.pneumoniae pneumonia cases had co-infections with other pathgens, consistent with the previous studies [ 12 , 17 ] .Two studies identified HRV as the most frequent co-pathogen [ 20 – 21 ],whereas other studies reported Streptococcus pneumoniae as the primary co-pathogen [ 22 – 23 ] .Clinical manifestations in cases with bacterial co-infection differed significantly from those with isolated C.pneumoniae but resembled bacterial infections[ 18 ] . However, these studies involved adults,about 50% aged over 60 years and had underlying diseases.These co-pathogens may only be local respiratory colonizer or synergistically contribute to the pathogenic process alongside C.pneumoniae. In our study, C.pneumoniae pneumonia presented relatively mild clinical manifestations and favorable therapeutic outcomes .Macrolides, tetracyclines and quinolones inhibit the synthesis of DNA and protein, are therefore recommended for C.pneumoniae Pneumonia treatment [ 24 ] .Most research reported that azithromycin or doxycycline retain efficacy against C.pneumonia.Low-dose glucocorticoids were administered in cases with suboptimal recovery while flexible bronchoscopy may be performed in patients with atelectasis or mucus plug obstruction. This study had some limitations.First,this study was a single-center study with a relatively short duration.Second,we only used nucleic acid testing for the detection of C.Pneumoniae,lacking serological examination and next-generation sequencing,which was different to identify current infection and chronic carrier.Third,we did not compare the clinical characteristics of C.pneumoniae infection single and co-infection with other pathogens due to limited sample size.Whether co-infection of exacerbate disease severity in pediatric C. pneumoniae pneumonia requires further investigation. In conclusion, our study demonstrated that the detection of C. pneumoniae in children exhibits an upward trend between 2023 to 2025.C.pneumoniae pneumonia predominantly affects children aged 6–15-years, characterized by cough, yellow sputum, fever, with unilateral lower-lobe parenchymal changes on imaging.Inflammatory markers are typically normal, complications are rare. Macrolides and/ doxycycline are effective, with favorable therapeuticoutcomes. Declarations C.pneumonia:Chlamydia pneumoniae;MP: Mycoplasma pneumonia;PCR: Polymer ase chain reaction; BALF: Bronchoalveolar lavage fluid ; RSV: Respiratory syncytial virus infection; HMPV: Human metapneumovirus; HBoV: Human bocavirus; HRV: Human rhinovirus; FluA: Influenza virus A; Flu B: Influenza virus B; PIV I-III: Parainfluenza virus I-III; ADV: Adenovirus; WBC: White blood cell; CRP: C-reactive protein. Ethics approval and consent to participate The study adhered to the Declaration of Helsinki and was approved by the Medical Ethics Committee of Children’s Hospital of Soochow Universi ty(Approval NO：Sdfey2023007).The parents of all study participants gave written informed consent before study enrollment. Consent for publication All authors have read and agreed to the published version of the manuscript. Availability of data and materials The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Competing interests The authors declare no competing interests. Funding This work was supported by the grant from Jiangsu Province Medical Science Research Project (Grant number K2023055), Suzhou Clinical Disease Key Special Project (Grant number LCZX202206), Suzhou Science and Techology Project (Grant numbers SYW2024003) Author contributions Conceived and designed the experiments: Yuqing Wang,Min Wu,Luting Zhou Collectted linlical date:Min Wu,Yeming Chen,Shun Wang,Ying Sun,Zhiqing Liu,Tianshu Liu， Contributed analysis tools and Analyzed the data: All authors. Writing—original draft preparation: Min Wu. Writing—review and editing: Yuqing Wang. Acknowledgements The authors are grateful to all technicians of the Diagnostic Microbiology Laboratory, the Children’s Hospital of Soochow University for technical contributions. 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06:46:00","extension":"xml","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":117736,"visible":true,"origin":"","legend":"","description":"","filename":"eeba857c76494607b4d729e1f6dcdfb21structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7333387/v1/a3e92cafc3c69d3a817b5eaf.xml"},{"id":92143497,"identity":"49ec6d2f-81a0-4be6-9e03-bbe3d9544c3d","added_by":"auto","created_at":"2025-09-25 06:38:00","extension":"html","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":126530,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7333387/v1/378c3c5a884379f176a0d633.html"},{"id":92143490,"identity":"4519f957-96ad-4a96-bc9a-7c0cdf712bd9","added_by":"auto","created_at":"2025-09-25 06:38:00","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":21296,"visible":true,"origin":"","legend":"\u003cp\u003eDetection of C.\u003cem\u003epneumoniae\u003c/em\u003e between January, 2023 to April, 2025\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7333387/v1/e0b9bd841699493aabc13ebb.png"},{"id":93400589,"identity":"d44bb83f-9f0b-4786-876f-0cf551b10f1f","added_by":"auto","created_at":"2025-10-13 12:24:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":873557,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7333387/v1/d19e06bf-8fff-45fe-9ac2-2dc05f1ed741.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Clinical characteristics of children hospitalized with Chlamydia pneumoniae pneumonia","fulltext":[{"header":"Background","content":"\u003cp\u003eC.pneumoniae is an atypial respiratory pathogen associated with community-acquired pneumonia,exhibiting periodic epidemic patterns \u003csup\u003e[1]\u003c/sup\u003e. As a strictly intracellularly parasitic prokaryote, it can persist in a carrier state or cause chronic infections \u003csup\u003e[2]\u003c/sup\u003e.Besides respiratory infections, C. pneumoniae has been linked to various chronic diseases such as atherosclerosis, Alzheimer's disease,asthma and chronic obstructive pulmonary disease \u003csup\u003e[3-6]\u003c/sup\u003e.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAccording to previous literatures,respiratory infections caused by C.pneumoniae\u0026nbsp;typically exhibit\u0026nbsp;a low incidence rate (0.17%~16.2%)\u003csup\u003e[7-10]\u003c/sup\u003e and relatively mild\u0026nbsp;clinical manifestations.Approximately\u0026nbsp;60-80% of C. pneumoniae infections is asymptomatic state and such infections\u0026nbsp;tend to progress\u0026nbsp;to a chronic or asymptomatic\u0026nbsp;state\u003csup\u003e[11]\u003c/sup\u003e.However,pulmonary imaging\u0026nbsp;findings in\u0026nbsp;C.pneumoniae pneumonia\u003c/p\u003e\n\u003cp\u003epredominantly\u0026nbsp;shows subpleural mass-like high-density shadows , which are prone to misdiagnosis as mycoplasma pneumonia,fungal pneumonia, tubercolous pneumonia, pulmonary embolism and other conditions.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eOwing to\u0026nbsp;variations in\u0026nbsp;detection\u0026nbsp;methodologies, the incidence of\u0026nbsp;C. pneumoniae\u0026nbsp;infection\u0026nbsp;exhibits significant variability.Additionally,the lack of\u0026nbsp;effective\u0026nbsp;\u003cem\u003eC. pneumoniae\u003c/em\u003edetection methods in some medical\u0026nbsp;institutions\u0026nbsp;further contributes to missed diagnoses and misdiagnoses.Several studies\u0026nbsp;\u003csup\u003e[10,12-13\u003c/sup\u003e]have reported a rising prevalence of C. pneumoniae in recent years. Accordingly, this study aims to analyze its clinical features to provide references for early diagnosis and treatment.\u0026nbsp;\u003c/p\u003e"},{"header":"METHODS","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003ePatients\u003c/h2\u003e\u003cp\u003eIn this study,the chidren hospitalized with community-acquired pneumonia in Department of Respiratory Medicine,Children\u0026rsquo;s Hospital of Soochow University, between January 1, 2023 to April 30, 2025 were enrolled.We then retrospectively analyzed the clinical data of those children diagnosed with C.pneumoniae infection.\u003c/p\u003e\u003cp\u003eThe exclusion criteria for this study were as follows: (1) patients with incomplete clinical data; (2) patients with hereditary metabolic diseases, neurological disorders, congenital heart disease, and/or immunodeficiency.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eDetection of respiratory pathogens analysis\u003c/h3\u003e\n\u003cp\u003ePolymerase chain reaction(PCR) was used to detect 13 tpyes of respiratory pathogens ,including respiratory syncytial virus infection (RSV), human metapneumovirus (HMPV), human bocavirus (HBoV), and human rhinovirus (HRV),influenza virus A (FluA), influenza virus B (Flu B), parainfluenza virus I-III(PIV I, PIV II, PIV III), adenovirus (ADV), and MP in Nasopharyngeal aspirate or bronchoalveolar lavage fluid (BALF) \u003csup\u003e[\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\u003cp\u003eBacterial dentification was performed using quantitative analysis by inoculating Nasopharyngeal aspirate or BALF samples onto selected media and incubated for 18\u0026ndash;24 h. Bacterial growth exceeding 10\u003csup\u003e3\u003c/sup\u003e colony-forming units/mL was regarded as clinically significant \u003csup\u003e[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e\n\u003ch3\u003eStatistical analyses\u003c/h3\u003e\n\u003cp\u003eData processing was conducted using SPSS 26.0statistical software(IBM, SPSS, Chicago, IL, USA).Measurement data that did not conform to a normal distribution, they were expressed as M(P\u003csub\u003e25\u003c/sub\u003e, P\u003csub\u003e75\u003c/sub\u003e),the inter-group comparisons were conducted using the rank sum test.The enumeration data was presented as counts or percentage.\u003c/p\u003e\u003cp\u003eP\u0026lt;0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"RESULTS","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003eDemographics characteristics and clinical symptoms\u003c/h2\u003e\u003cp\u003eIn this study,a total of 15144 hospitalized children with community-acquired pneumonia were included,260(1.71%,260/15144) had \u003cem\u003eC. pneumoniae\u003c/em\u003e infection.The The detectable rate of C.\u003cem\u003epneumoniae\u003c/em\u003e were 4.24% in 2023,26.52% in 2024 and 34,89%between January,1 to April, 30,2025.Both the number of detected cases and detection rate of \u003cem\u003eC. pneumoniae\u003c/em\u003e in this study showed an obvious upward trend since 2023.Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eAfter applying the exclusions criteria, 226 cases with complete data were enrolled for analysis.Among the 226 patients,153 (67.70%) were male and 73 (32.30%) were female,the male-to-female ratio was 2:1. The average length of hospital stay was 6.54\u0026thinsp;\u0026plusmn;\u0026thinsp;1.59 days.The age of patients ranged from 3 years to 18 years.5 patients (2.21%)were aged\u0026thinsp;\u0026le;\u0026thinsp;6years, 206 (91.15%) patients were aged between 6\u0026ndash;15 years,and15(6.63%)patients were aged\u0026thinsp;\u0026ge;\u0026thinsp;15 years.The median age was 11.2 (9.5, 13.0)years.Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eThe most common clinical symptoms were cough (100%, 226/226), fever (39.38%, 89/226), and chest pain(3.98%, 9/226),wheeze(2.21%, 5/226),tachypnea (0.44%, 1/226). Among the 89 feverish patients,28 (12.39%) had low fever(T\u0026lt;38℃),40(17.70%) had moderate fever(38\u0026thinsp;\u0026le;\u0026thinsp;T\u0026lt;39℃), and 21 (9.29%) had high fever(T\u0026thinsp;\u0026ge;\u0026thinsp;39℃).The median duration of fever before admission was 5.0(3.0, 7.0)days.Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\u003cp\u003eThe duration of coughing before admission ranged from 1-30days.The median duration was 7(5.0\u0026ndash;10.0)days.The symptom of cough included dry cough(13.71%,31/226) and wet cough(86.28%,195/226)).95 (42.60%, 95/226) could expectorate yellow sputum.No patients presented with cyanosis or dyspnea.Upon lung auscultation, 136 cases (60.17%, 136/226) showed no rales, 69 cases (30.53%, 69/226) had moist rales, and only 5 cases had wheezing.Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\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\u003eDetection of C.\u003cem\u003epneumoniae\u003c/em\u003e between January, 2023 to April, 2025\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"10\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" 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=\"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\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c9\" colnum=\"9\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c10\" colnum=\"10\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u003cp\u003emonth\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c4\" namest=\"c2\"\u003e\u003cp\u003e2023\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c7\" namest=\"c5\"\u003e\u003cp\u003e2024\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colspan=\"3\" nameend=\"c10\" namest=\"c8\"\u003e\u003cp\u003e2025\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003einpatients\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003edetected cases\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eDetection rate\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003einpatients\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c6\"\u003e\u003cp\u003edetected cases\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c7\"\u003e\u003cp\u003eDetection rate\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c8\"\u003e\u003cp\u003einpatients\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c9\"\u003e\u003cp\u003edetected cases\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c10\"\u003e\u003cp\u003eDetection rate\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e371\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e573\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.35\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e460\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e25\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e5.43\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e400\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.50\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e543\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e412\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e40\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e9.70\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e721\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.83\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e535\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e403\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e20\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e4.96\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e678\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.59\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e449\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e\u003cp\u003e410\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c9\"\u003e\u003cp\u003e61\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c10\"\u003e\u003cp\u003e14.8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e666\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.60\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e428\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e2.33\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e645\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.77\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e452\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.99\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e692\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e524\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e0.95\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e692\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.14\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e459\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.96\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e658\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e440\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e1.81\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e712\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e466\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e16\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e3.43\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e11\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e678\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e469\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e8.52\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e12\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e\u003cp\u003e693\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e\u003cp\u003e0.00\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e515\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e\u003cp\u003e18\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e\u003cp\u003e3.49\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c8\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c9\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c10\"\u003e\u0026nbsp;\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=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eclinical characteristics of C.pneumoniae pneumonia\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePatient characteristics\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCase\u003c/p\u003e\u003cp\u003eN(%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSex (male/female)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e153/73\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emedian age(years)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11.2(9.5\u0026ndash;13.0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ehospital stays(days)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.54\u0026thinsp;\u0026plusmn;\u0026thinsp;1.59\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThe duration of coughing\u003c/p\u003e\u003cp\u003ebefore admission(days)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7(5.0, 10.0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eThe duration of fever\u003c/p\u003e\u003cp\u003ebefore admission(days)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5(3.0, 7.0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge group\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026le;6years\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5(2.21)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e6-15years\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e206(91.15)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;15years\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e15(6.63)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ecough\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e226(100)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003edry cough\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e31(13.71)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWet cough\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e195(86.28)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ewhite sputum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17(7.52)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eYellow sputum\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e95(42.60)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCannot cough up phlegm\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e83(36.72)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003efever\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e89(39.38)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003elow fever(T\u0026lt;38℃)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28(12.39)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emoderate fever(38℃\u0026le;T\u0026lt;39℃)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e40(17.70)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ehigh fever(T\u0026thinsp;\u0026ge;\u0026thinsp;39℃)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21(9.29)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003echest pain\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9(3.98)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ewheeze\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5(2.21)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epolypnea\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1(0.44)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ecyanosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0(0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003edyspnea\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0(0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePulmonary signs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emoist rales\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e69(30.53)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWheezing rales\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5(2.21)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emoist and Wheezing rales\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e11(4.86)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eabsence signs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e136(60.17)\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\u003eImaging features\u003c/h2\u003e\u003cp\u003eAmong the 226 patients with Chlamydia pneumoniae pneumonia,180 (79.64%,180/226)cases had unilateral lung involvement.The lesion most commonly occurred in the lower lobes of the lungs,31.85% (72//226) in the right lower lobe and 21.68% (49/226) in the left lower lobe; 6.64% (15/226) of the patients had lesions involving more than two lung lobes. Imaging examination revealed that 92.92% (210/226) of the patients had massive high-density shadows.Pulmonary complications of Chlamydial pneumoniae pneumonia identified by imaging include 9(3.98%, 9/226)cases of atelectasis,8༈3.54%, 8/226༉cases of pleural effusion,3༈1.33%, 3/226༉case of bronchiectasia.Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\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\u003eImaging features of C.pneumoniae pneumonia\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003echest imaging\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCase\u003c/p\u003e\u003cp\u003eN(%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSite of pneumonia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRight lung\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e109(48.23)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003esuperior lobe of right lung\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e18(7.96)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emiddle lobe of right lung\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e12(5.31)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003einferior lobe of right lung\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e72(31.85)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emiddle lob、inferior lobe of right lung\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7(3.09)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLeft lung\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e71(31.42)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003esuperior lobe of left lung\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e14(6.20)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003einferior lobe of left lung\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e49(21.68)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003esuperior lobe、inferior lobe of left lung\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8(3.54)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eboth lungs\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e46(20.35)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epulmonary complications\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePulmonary atrophy\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9(3.98)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epleural effusion\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e8(3.54)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ebronchiectasia\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3(1.33)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epulmonary embolism\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0(0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003elung necrosis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0(0)\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\n\u003ch3\u003elaboratory examination results\u003c/h3\u003e\n\u003cp\u003eThe white blood cell count was 9.6 (7.8, 11.3) \u0026times; 10\u003csup\u003e9\u003c/sup\u003e/L, with a neutrophil proportion of 62.3% (57%, 68%). A total of 70.83% of patients had an elevated platelet count (greater than 300 \u0026times;10\u003csup\u003e9\u003c/sup\u003e /L), with a median of 320(270, 382༉\u0026times; 10\u003csup\u003e9\u003c/sup\u003e /L.84 (37.16%,) cases had elevated blood C-reactive protein, with a median of 6.5mg/dl༈2.7, 17.5༉. Additionally, 69(30.53%) cases had elevated LDH levels.90(39.82%)cases had elevated D-dimer levels.Indicators related to humoral immunity and cellular immunity were generally within normal ranges.Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\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\u003elaboratory examination results of Chlamydia pneumoniae pneumonia\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003elaboratory examination\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCase\u003c/p\u003e\u003cp\u003eN(%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWBC count\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9.6(7.8, 11.3)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;4\u0026times;109 /L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1(0.44)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e4\u0026thinsp;~\u0026thinsp;10\u0026times;109 /L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e127(56.19)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;10\u0026times;109 /L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e98(53.36)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eN%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e62.3(57, 68)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;50%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e20(8.85)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e50%~70%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e161(71.24)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;70%\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e45(19.91)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCRP(mg/l)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e6.5(2.7, 17.5)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026ge;\u0026thinsp;8mg/l\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e84(37.16)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;8mg/l\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e142(62.83)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePLT\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e320(270, 382)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;100\u0026times;109 /L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1(0.44)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e100\u0026thinsp;~\u0026thinsp;300\u0026times;109 /L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e72(31.86)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;300\u0026times;109 /L\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e153(70.83)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLDH(U/L)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e262(228, 309)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026le;\u0026thinsp;295U/L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e151(66.81)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;295U/L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e69(30.53)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eD-dimer(ug/L)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e410(297, 592)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026le;\u0026thinsp;500U/L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e136(60.18)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u0026gt;\u0026thinsp;500U/L\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e90(39.82)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAPTT(s)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e39.7(36.3, 43.8)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFDP(ug/L)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2330(1590, 2330)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCD3CD4(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e33.06\u0026thinsp;\u0026plusmn;\u0026thinsp;9.36\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCD3CD8(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e28.73\u0026thinsp;\u0026plusmn;\u0026thinsp;8.53\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCD19(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e17.01\u0026thinsp;\u0026plusmn;\u0026thinsp;7.01\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCD16CD56(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e12.16\u0026thinsp;\u0026plusmn;\u0026thinsp;6.98\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCD19CD23(%)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e9.60\u0026thinsp;\u0026plusmn;\u0026thinsp;4.74\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eLgA\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.77\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003elgG\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e12.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.40\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003elgM\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1.63(1.28, 2.09)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\n\u003ch3\u003eDetection of co-infection\u003c/h3\u003e\n\u003cp\u003eA total of 93(35.50%) cases were detected with co-infections. The most commonly identified pathogens were viruses (27.87%). Among the detected viruses, HRV (20.8%)was the most common, followed by ADV (3.10%,7/226). Mixed bacterial infections were detected in 21 case, including Streptococcus pneumoniae(5.31%)、Moraxella catarrhalis(2.21%) and Haemophilus influenzae(1.77%).Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\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\u003eThe co-infection pathogen of Chlamydia pneumoniae pneumonia\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003epathogen\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCase\u003c/p\u003e\u003cp\u003eN(%)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003evirus\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e63(27.87)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHRV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e47(20.80)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eADV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e7(3.10)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ehMPV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3(1.33)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ePIV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2(0.88)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFlu\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2(0.88)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRSV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1(0.44)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHBoV\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1(0.44)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMP\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e0(0)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003ebacteria\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e21(9.29)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eStreptococcus pneumoniae\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e12(5.31)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eMoraxella catarrhalis\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e5(2.21)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eHaemophilus influenzae\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e4(1.77)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eBronchoscopy and BALF collection\u003c/h2\u003e\u003cp\u003eAmong the 226 patients, 51 (22.56%) underwent flexible bronchoscopy and bronchoalveolar lavage .All 51 cases tested positive for Chlamydia nucleic acid in BALF.The primary finding under bronchoscopy was a large amount of white fluffy exudate (19.91%,45/226) in the affected lung lobes, and sputum plugs observed in 2 cases.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003eTreatment\u003c/h2\u003e\u003cp\u003eAll children with C.pneumoniae Pneumonia received treatment with azithromycin or doxycycline. Glucocorticoid therapy was administered to 123(54%)cases due to the slow improvement of the cough symptoms and delayed absorption of the lung lesions.\u003c/p\u003e\u003cp\u003eAll the patients were followed up for 2 months after discharge.Symptoms resolved completely with lesions absorption confirmed by imaging.No respiratory support, intensive care admission or deaths occurred.\u003c/p\u003e\u003c/div\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThe overall prevalence rate of C.pneumoniae pneumonia in children and adults was 3.5% (95% CI 2.2% \u0026minus;\u0026thinsp;4.9%) \u003csup\u003e[\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/sup\u003e.The detection rate in the present study was 1.71%, which was higher than the 0.34% reported in Beijing 2015\u0026ndash;2019\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e but lower than the 6.5% reported in a Japanese study\u003csup\u003e[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e.This discrepancy may be attributed to the fact that C.pneumoniae diagosis in our study was based on real-time PCR,whereas the Japanese study employed three distinct detection methods.Additionally, the Japanese study had a limited sample size of clinical data(232 cases) and included adults populations.\u003c/p\u003e\u003cp\u003eIn the present study,the detection rate of C. pneumoniae exhibited an upward trend starting from 2023,with an approximate 6-fold increase in 2024.This trend is consistent with previous studies \u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e.In Marseille,Sophie Edouard reported a 19-fold increase of Chlamydia pneumoniae diagnoses in 2024 and he acquired four C.pneumoniae genomes, all belonging to serotype ST16. The increased detection rate of C.pneumoniae may be related to multiple factors. First, Chlamydia pneumoniae infection exhibits periodic epidemic pattern with geographical variations in cycle durations,approximately 4\u0026ndash;6 year cycles\u003csup\u003e[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]\u003c/sup\u003e .Starting from October 2024, especially since 2025,the detection incidence of C.pneumoniae has significantly increased,indicating that C.pneumoniae is entering its epidemic peak again.Second, following the COVID-19 pandemic, children's respiratory immunity has been impacted by the successive prevalence of the RSV,MP and influenza virus ,leading to increased susceptibility to subsequent C.pneumoniae infection.Additionally,the popularization of molecular diagnostic techniques has played a role: multiplex PCR have been widely adopted, markedly improving the detection rate of asymptomatic or mild infections.\u003c/p\u003e\u003cp\u003eIn the present study,children with \u003cem\u003eC. pneumoniae\u003c/em\u003e pneumonia predominantly affect those aged 6\u0026ndash;15 years, with a median age of 11.2 years. The study\u003csup\u003e[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e reported in China showed that the highest incidence was in 10\u0026ndash;14 years old while in France was between 10\u0026ndash;15 years\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]\u003c/sup\u003e.Therefore, C.pneumoniae pneumonia mainly occurs in older children.\u003c/p\u003e\u003cp\u003eThe main symptoms included cough ,yellow sputum and fever, chest pain and wheezing were relatively rare,only one case presented with hemoptysis.Inflammatory markers such as blood cell count,C-reactive protein,LDH,D-dimer were mostly normal ranges, similar to previous reports\u003csup\u003e[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e.Chest imaging findings predominantly present with unilateral pulmonary involvement and mass-like high-density opacities.In contrast,Wen\u003csup\u003e[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]\u003c/sup\u003e reported 10 cases of C.pneumoniae pneumonia ,4 cases manifested with chest pain.They identified that the common chest imaging findings was a subpleural highdensity mass-like shadow with a halo sign,which may account for the occurrence of chest pain.\u003c/p\u003e\u003cp\u003eIn this study,35.50% of the C.pneumoniae pneumonia cases had co-infections with other pathgens, consistent with the previous studies\u003csup\u003e[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]\u003c/sup\u003e.Two studies identified HRV as the most frequent co-pathogen\u003csup\u003e[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e],whereas other studies reported Streptococcus pneumoniae as the primary co-pathogen\u003csup\u003e[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]\u003c/sup\u003e.Clinical manifestations in cases with bacterial co-infection differed significantly from those with isolated C.pneumoniae but resembled bacterial infections[\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]\u003c/sup\u003e. However, these studies involved adults,about 50% aged over 60 years and had underlying diseases.These co-pathogens may only be local respiratory colonizer or synergistically contribute to the pathogenic process alongside C.pneumoniae.\u003c/p\u003e\u003cp\u003eIn our study, C.pneumoniae pneumonia presented relatively mild clinical manifestations and favorable therapeutic outcomes .Macrolides, tetracyclines and quinolones inhibit the synthesis of DNA and protein, are therefore recommended for C.pneumoniae Pneumonia treatment \u003csup\u003e[\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]\u003c/sup\u003e.Most research reported that azithromycin or doxycycline retain efficacy against C.pneumonia.Low-dose glucocorticoids were administered in cases with suboptimal recovery while flexible bronchoscopy may be performed in patients with atelectasis or mucus plug obstruction.\u003c/p\u003e\u003cp\u003eThis study had some limitations.First,this study was a single-center study with a relatively short duration.Second,we only used nucleic acid testing for the detection of C.Pneumoniae,lacking serological examination and next-generation sequencing,which was different to identify current infection and chronic carrier.Third,we did not compare the clinical characteristics of C.pneumoniae infection single and co-infection with other pathogens due to limited sample size.Whether co-infection of exacerbate disease severity in pediatric C. pneumoniae pneumonia requires further investigation.\u003c/p\u003e\u003cp\u003eIn conclusion, our study demonstrated that the detection of C. pneumoniae in children exhibits an upward trend between 2023 to 2025.C.pneumoniae pneumonia predominantly affects children aged 6\u0026ndash;15-years, characterized by cough, yellow sputum, fever, with unilateral lower-lobe parenchymal changes on imaging.Inflammatory markers are typically normal, complications are rare. Macrolides and/ doxycycline are effective, with favorable therapeuticoutcomes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eC.pneumonia:Chlamydia pneumoniae;MP: Mycoplasma pneumonia;PCR: Polymer\u003c/p\u003e\n\u003cp\u003ease chain reaction; BALF: Bronchoalveolar lavage fluid\u0026nbsp;; RSV: Respiratory syncytial virus infection; HMPV: Human metapneumovirus; HBoV: Human bocavirus; HRV: Human rhinovirus;\u0026nbsp;FluA: Influenza virus A;\u0026nbsp;Flu B: Influenza virus B; PIV I-III: Parainfluenza virus I-III; ADV: Adenovirus; WBC: White blood cell; CRP: C-reactive protein.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study adhered to the Declaration of Helsinki\u0026nbsp;and was approved by the Medical Ethics Committee of Children\u0026rsquo;s Hospital of Soochow Universi ty(Approval NO：Sdfey2023007).The parents of all study participants gave written informed consent before study enrollment.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors have read and agreed to the published version of the manuscript.\u0026nbsp;\u003cbr\u003e\u0026nbsp;\u003cstrong\u003eAvailability of data and materials\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ethe corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the grant from Jiangsu Province Medical Science\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eResearch Project (Grant number K2023055), Suzhou Clinical Disease Key Special\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eProject (Grant number LCZX202206), Suzhou Science and Techology Project (Grant\u0026nbsp;\u003c/p\u003e\n\u003cp\u003enumbers SYW2024003)\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eConceived and designed the experiments: Yuqing Wang,Min Wu,Luting Zhou\u003c/p\u003e\n\u003cp\u003eCollectted linlical date:Min Wu,Yeming Chen,Shun Wang,Ying Sun,Zhiqing Liu,Tianshu Liu，\u003c/p\u003e\n\u003cp\u003eContributed analysis tools and Analyzed the data: All authors.\u003c/p\u003e\n\u003cp\u003eWriting\u0026mdash;original draft preparation: Min Wu.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWriting\u0026mdash;review and editing: Yuqing Wang.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors are grateful to all technicians of the Diagnostic Microbiology Laboratory,\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ethe Children\u0026rsquo;s Hospital of Soochow University for technical contributions.\u0026nbsp;\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eThom DH，Grayston JT．Infections with Chlamydia pneumoniae strain TWAR［J］．Clin Chest Med,1991,12( 2) : 245－256．\u003c/li\u003e\n \u003cli\u003eSharma L,Losier A,Tolbert T,et al.Atypical pneumonia: updates on Legionella Chlamydophila，and Mycoplasma pneumonia［J］．Clin Chest Med,2017,38( 1) : 45－58．\u003c/li\u003e\n \u003cli\u003eKhoshbayan A，Taheri F，Moghadam MT，et al．The association of Chlamydia pneumoniae infection with atherosclerosis: review and update of in vitro and animal studies［J］．Microb Pathog,2021,154: 104803．\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eSubedi L,Gaire BP，Koronyo Y,et al.Chlamydia pneumoniae in Alzheimer\u0026apos;s disease pathology［J］.Front Neurosci,2024,18: 1393293．\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eCalmes D,Huynen P，Paulus V，et al．Chronic infection with Chlamydia pneumoniae in asthma: a type-2 low infection related phenotype［J］.ＲespirＲes.2021.22( 1) : 72．\u0026nbsp;\u003c/li\u003e\n \u003cli\u003eYildiz S,Gonullu N,Yildiz BP,et al.The role of typical and atypical pathogens in acute exacerbations of chronic obstructive pulmonary disease［J］.ClinＲespir J,2021,15( 2) : 209－215．\u003c/li\u003e\n \u003cli\u003eHan HY, Moon JU, Rhim JW, et al. Surge of Chlamydia pneumoniae pneumonia in children hospitalized with community‑acquired pneumonia at a single center in korea in 2016[J]. J Infect Chemother, 2023, 29(5): 453‑457. DOI: 10.1016/j.jiac.2023.01.012.\u0026nbsp;\u003c/li\u003e\n \u003cli\u003ePuljiz I, Kuzman I, Dakovic‑Rode O, et al. Chlamydia pneumoniae and Mycoplasma pneumoniae pneumonia: comparison of clinical, epidemiological characteristics and laboratory profiles[J]. Epidemiol Infect, 2006, 134(3): 548‑555. DOI: 10.1017/S0950268805005522.\u003c/li\u003e\n \u003cli\u003eMerida Vieyra J, De Colsa Ranero A, Palacios Reyes D, et al.Chlamydophila pneumoniae‑associated community‑acquired pneumonia in paediatric patients of a tertiary care hospital in Mexico: molecular diagnostic and clinical insights[J]. Sci Rep, 2023, 13(1):21477. DOI: 10.1038/s41598‑023‑48701‑5.\u003c/li\u003e\n \u003cli\u003eDehua,Yang,Yingshuo,Wang S, et al. Epidemic trend and clinical features of Chlamydia pneumoniae infection in children in Hangzhou area［J］,Chinese Journal of New Clinical Medicine,November 2024,Volume 17,Number 11:1210-1214.\u003c/li\u003e\n \u003cli\u003eJama-Kmiecik A,Frej-Mądrzak M, Sarowska J, et al. [Selected aspects of Chlamydophila pneumoniae infections]. Postepy Hig Med Dosw (Online), 2015. 69: p. 612-23.\u003c/li\u003e\n \u003cli\u003eEdouard S,Attamna\u0026nbsp;R,et al.Significant rise of Chlamydia pneumoniae infection in 2024 in Marseille, France［J］. Int J Infect Dis, 2025. 155: p. 107897.\u003c/li\u003e\n \u003cli\u003eTagini F, Opota O, Greub G. Chlamydia pneumoniae Upsurge at Tertiary Hospital, Lausanne, Switzerland. Emerg Infect Dis. 2024;30(4):810‑2. doi: 10.3201/eid3004.231610.\u003c/li\u003e\n \u003cli\u003eJiang W, Mao L, Wang K, Wang Y, Hao C, Shao X, Xu J. Prevalence of B. pertussis infection in children with clinically suspected pertussis. J Microbiol Immunol Infect. 2021;54(4):693\u0026ndash;700.\u003c/li\u003e\n \u003cli\u003eYu-Qing W, Hao C-L, Wei J, Zheng-Rong C, Xin-Xin Z, Wen-Jing G. Etiology and Clinical Characteristics of Community-Acquired Pneumonia with Airway Malacia in Children. J Trop Pediatr. 2018;64(4):317\u0026ndash;25.\u003c/li\u003e\n \u003cli\u003eWang S, Tang J, Tan Y, et al. Prevalence of atypical pathogens in patients with severe pneumonia: a systematic review and meta‑analysis[J]. BMJ .Open,2023,13(4):e066721.\u003c/li\u003e\n \u003cli\u003eLuo, M., et al., [Epidemiological characteristics of Chlamydia pneumoniae in cases with acute \u0026nbsp; respiratory infection in Beijing, 2015-2019]. Zhonghua Liu Xing Bing Xue Za Zhi, 2021. 42(8): p. 1466-1474.\u003c/li\u003e\n \u003cli\u003eMiyashita, N., et al. Community-acquired Chlamydia pneumoniae pneumonia in Japan: a prospective multicenter community-acquired pneumonia study. Intern Med, 2002. 41(11): p. 943-9.\u003c/li\u003e\n \u003cli\u003eXiaohui Wen, Huimin,Li.et al.Clinical features of Chlamydia pneumoniae pneumonia in 10 children. Chin J Pediatr, April 2025, Vol. 63, No. 4.\u003c/li\u003e\n \u003cli\u003eMantelli C, Colson P, Lesage L, Stoupan D, Chaudet H, Morand A, et al. Coinfections and iterative detection of respiratory viruses among 17,689 patients between March 2021 and December 2022 in Southern France. J ClinVirol.2024;175:105744.\u003c/li\u003e\n \u003cli\u003eTagini F, Opota O, Greub G. Chlamydia pneumoniae Upsurge at Tertiary Hospital,Lausanne, Switzerland. Emerg Infect Dis. 2024;30(4):810‑2. doi:10.3201/eid3004.231610.\u003c/li\u003e\n \u003cli\u003eSaito A, Kohno S, Matsushima T,Suttithawil W, Wangroongasrb P, Naigowit P, Nunthapisud P, Chantadisai N, Ploysongsang Y. Chlamydophila {Chlamydia) pneumoniae as a cause of community-acquire pneumonia in Thailand. J MedAssoc Thai 84:43.\u003c/li\u003e\n \u003cli\u003eMiyashita N, Fukano H, Niki Y, Matsushima T, Okimoto N. Etiology of community-acquired pneumonia requiring hospitalization in Japan. Chest 119:1295-1296,2001.\u003c/li\u003e\n \u003cli\u003eGeorgakopoulou VE, Lempesis IG, Tarantinos K, et al. Atypical pneumonia (review) [J]. Exp Ther Med, 2024, 28(5):424..\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Chlamydia pneumoniae, Pneumonia, Chidren, Clinical characteristics","lastPublishedDoi":"10.21203/rs.3.rs-7333387/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7333387/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e Chlamydia pneumoniae is an atypical respiratory pathogen that contributes to community-acquired pneumonia in children. However,the clinical manifestations are often non-specific, posing challenges for early identification. The purpose of this study is to summarize the Clinical characteristics of Chlamydia pneumoniae pneumonia in children,thereby facilitating its recognition prior to the availability of pathogen detection results.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eChildren hospitalized with community-acquired pneumonia between January 1, 2023 to April 30, 2025 in the Department of Respiratory Medicine,Children’s Hospital of Soochow University were enrolled. Nasopharyngeal aspirates or BALF were collected for respiratory pathogen detection and medical records of C. pneumoniae infection were retrospectively collected.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eOf 15144 hospitalized children with community-acquired pneumonia, 260(1.71%,260/15144) had C. pneumoniae infection.After exclusions criteria, 226 cases with complete data were analyzed.Among the 226 children,the male-to-female ratio was 2:1 with a median age of 11.2 (9.5-13.0)years.Of which,206 (91.15%) patients were aged between 6–15 years old .The average length of hospital stay was 6.54±1.59 days.The most common symptoms were cough (100%), yellow sputum (42.60%),fever (39.38%).The median duration from onset to admission was 7(5.0,10.0)days and median pre-admission fever durations of 5.0(3.0,7.0)days. Radiological examination showed that 95.13% had pulmonary parenchymal changes; 9.64% had unilateral involvement.,mostly in the right lower lobe (31.85%)and 49 left lower lobes(21.68%). Lesions in ≥2 lobes occurred in 6.64% Complications included atelectasis（3.98%）,pleural effusion（3.54%）,and bronchiectasia（1.33%）.\u003c/p\u003e\n\u003cp\u003eAll cases were treated with azithromycin or doxycycline，51 cases (22.56%)received fiberoptic bronchoscopy and lavage treatment,with full recovery and no severe outcomes.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003eThe detection of C. pneumoniae in children has an increasing trend.C. pneumoniae pneumonia mainly occurs in 6–15-years, characterized by cough, yellow sputum, fever, unilateral lower-lobe parenchymal changes on imaging. Inflammatory markers are normal, complications rare. Macrolides/doxycycline work well with good outcomes.\u003c/p\u003e","manuscriptTitle":"Clinical characteristics of children hospitalized with Chlamydia pneumoniae pneumonia","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-09-25 06:37:55","doi":"10.21203/rs.3.rs-7333387/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"e4c13afc-643f-44ba-a6dc-8a962c5eee40","owner":[],"postedDate":"September 25th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-10-13T12:23:56+00:00","versionOfRecord":[],"versionCreatedAt":"2025-09-25 06:37:55","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7333387","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7333387","identity":"rs-7333387","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}