Data analysis from the Sepsis Registry study on the association between antibiotic use duration and clinical outcomes in neonatal sepsis

Data analysis from the Sepsis Registry study on the association between antibiotic use duration and clinical outcomes in neonatal sepsis | 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 Data analysis from the Sepsis Registry study on the association between antibiotic use duration and clinical outcomes in neonatal sepsis Weixiao Hu, Zhenhai Qiu, Dachun Wang, Li Zhang, Jie Tong This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9153479/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract Background Timely initiation of antibiotic therapy is a cornerstone of sepsis management, yet evidence supporting strict time-based targets in neonatal sepsis remains limited and inconsistent. Whether incremental delays in time-to-antibiotic (TTA) administration are independently associated with adverse outcomes in neonates is uncertain. Methods We conducted a multicenter retrospective cohort study using a neonatal sepsis registry from five centers between January 2018 and December 2023. Hospitalized neonates with clinically diagnosed sepsis and documented TTA were included. TTA was analyzed as both a continuous variable and categorized into 6 h, with an additional binary comparison of early (< 1 h) versus delayed (≥ 1 h) administration. The primary outcome was in-hospital mortality. Secondary outcomes included hospital length of stay, duration of mechanical ventilation, secondary infection, and a composite adverse outcome. Multivariable logistic regression and Cox proportional hazards models were used to estimate adjusted associations, controlling for prespecified clinical covariates. Results Among 1,500 neonates with sepsis, median TTA was 0.76 hours, and 58.0% received antibiotics within 1 hour. Overall in-hospital mortality was 15.9%. Mortality increased modestly across TTA categories, from 15.3% ( 6 h) (trend P ≈ 0.024). In adjusted analyses, each 1-hour delay in antibiotic administration was associated with a higher, but not statistically significant, odds of mortality (adjusted OR 1.090; 95% CI 0.975–1.217). Kaplan–Meier analyses demonstrated significant survival differences across detailed TTA strata, whereas the binary comparison of < 1 h versus ≥ 1 h was not significant. Longer TTA was associated with a small increase in hospital length of stay, while other secondary outcomes showed no clear linear association. Subgroup and sensitivity analyses yielded directionally consistent results. Conclusions In this multicenter cohort of neonates with sepsis, longer delays in antibiotic administration were associated with modestly worse outcomes, with excess risk concentrated among more prolonged delays rather than marginal deviations beyond 1 hour. These findings support efforts to minimize extreme treatment delays while suggesting that rigid application of a universal 1-hour threshold may not fully capture risk heterogeneity in neonatal sepsis. Neonatal sepsis time-to-antibiotic antibiotic timing in-hospital mortality multicenter cohort study Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Neonatal sepsis remains a leading cause of morbidity and mortality worldwide, particularly among preterm and low–birth weight infants, despite advances in perinatal care and antimicrobial therapy[ 1 – 3 ]. The burden is especially pronounced in low- and middle-income settings, but substantial mortality persists even in high-resource neonatal intensive care units (NICUs) [ 4 – 6 ]. Early recognition and timely initiation of appropriate antimicrobial therapy are therefore central components of neonatal sepsis management and are emphasized across international guidelines[ 7 – 9 ]. In adult and pediatric populations, a robust body of evidence supports the concept that delays in antibiotic administration are associated with increased mortality in sepsis and septic shock [ 10 – 12 ]. This evidence has driven the widespread adoption of time-based performance metrics, most notably the “1-hour bundle,” which prioritizes prompt antibiotic delivery following sepsis recognition [ 13 – 16 ]. However, extrapolation of these findings to neonates is not straightforward. Neonatal sepsis differs fundamentally in its pathophysiology, clinical presentation, pathogen spectrum, and host immune response, and neonates are uniquely vulnerable to both undertreatment and overtreatment with antibiotics [ 1 , 17 , 18 ]. Existing evidence on the relationship between time-to-antibiotic (TTA) administration and outcomes in neonatal sepsis is limited and inconsistent. Several single-center studies and secondary analyses suggest potential harm associated with prolonged delays, particularly in critically ill or extremely preterm infants [ 19 – 21 ]. In contrast, other investigations have reported weak or non-significant associations once illness severity and perinatal factors are accounted for, raising questions about whether a universal 1-hour threshold is appropriate for all neonatal populations[ 3 , 14 , 22 ]. Importantly, most prior studies have been constrained by small sample sizes, heterogeneous definitions of exposure, limited adjustment for confounding, or binary categorizations of TTA that may obscure non-linear risk patterns. Moreover, neonatal sepsis encompasses both early-onset sepsis (EOS), typically related to perinatal transmission, and late-onset sepsis (LOS), often associated with nosocomial or community-acquired pathogens. These entities differ in timing, microbiology, and clinical trajectory, yet are frequently pooled in analyses without formal interaction testing [ 3 , 21 ]. Multicenter data capturing contemporary practice patterns, center-level variation, and detailed timing of antibiotic initiation remain scarce. To address these gaps, we conducted a large multicenter retrospective cohort study using a standardized neonatal sepsis registry from five centers over a six-year period. Our objectives were to (1) characterize the distribution of TTA in routine clinical practice, (2) examine the association between incremental delays in antibiotic administration and in-hospital mortality using both continuous and categorical exposure definitions, and (3) explore potential effect modification across clinically relevant subgroups, including EOS versus LOS, gestational age, and illness severity. We further evaluated secondary outcomes related to healthcare utilization and complications to provide a comprehensive assessment of the clinical impact of antibiotic timing in neonatal sepsis. Methods Study design and data source This was a multicenter retrospective cohort study using the Sepsis Registry from five centers between January 2018 and December 2023, including hospitalized neonates with clinically diagnosed sepsis. Data extraction captured demographics, clinical variables, treatments, and outcomes from the registry; analysis followed a prespecified statistical plan. Population and eligibility We included 1,500 neonates with sepsis who received intravenous antibiotics and had documented time-to-antibiotic (TTA). Key exclusions in the registry preprocessing were missing TTA, missing survival outcome, or duplicate encounters. Early-onset sepsis (EOS) and late-onset sepsis (LOS) were both retained (EOS 56.8%, LOS 43.2%). Exposure definition The main exposure was TTA, defined as hours from admission/diagnosis to first intravenous antibiotic dose, treated as a continuous variable and categorized as 6 h. A binary comparison of early (< 1 h) versus delayed (≥ 1 h) administration was also examined. Outcomes Primary outcome: in-hospital mortality. Secondary outcomes: hospital length of stay (LOS), mechanical ventilation duration, secondary infection, and a composite adverse outcome (per study plan). Covariates Prespecified covariates: gestational age, birth weight, 5-minute Apgar score, illness severity score, sepsis type (EOS/LOS), respiratory distress syndrome (RDS), necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), blood culture positivity, and major pathogen category. Statistical analysis Baseline characteristics were summarized overall and by early vs delayed groups; group differences used appropriate univariable tests (Table 1, Fig. 1 ). Mortality was described across TTA strata with trend testing (Table 2, Fig. 2 A) and binary early vs delayed comparison (Fig. 2 C). Multivariable logistic regression estimated the adjusted odds ratio (OR) for mortality per 1-hour delay, adjusting for the prespecified covariates (Table 3, Fig. 2 B/Fig. 4 “Overall”). Cox proportional hazards models estimated hazard ratios (HR) for time-to-event mortality; Kaplan–Meier curves with log-rank tests compared survival across TTA strata and by < 1 h vs ≥ 1 h (Fig. 3 ). Subgroup analyses were predefined (EOS/LOS, gestational age strata, severity strata) with interaction assessment; center-level comparisons were descriptive (Fig. 4 , Fig. 6 ). Sensitivity analyses: culture-positive only, excluding extremely preterm, EOS-only, and period-specific analyses (2018–2020 vs 2021–2023) (Supplementary Table). Secondary outcomes were compared across TTA categories with trend tests (Fig. 5 ). Two-sided P < 0.05 indicated statistical significance. Analyses were performed per the prespecified plan; no multiplicity adjustments were applied. Results Study population and baseline characteristics We analyzed 1,500 neonates (5 centers). Median gestational age was 35.0 weeks (IQR 32.3–37.6), median birth weight 3,486 g; 55.1% were male. EOS accounted for 56.8%, and blood cultures were positive in 64.1% (Table 1, Fig. 1 A–F). Median TTA was 0.76 hours; 58.0% received antibiotics within 1 hour and 91.2% within 3 hours (Fig. 1 C). Early (< 1 h) and delayed (≥ 1 h) groups had similar gestational age and birth weight; the early group showed slightly higher severity scores (median 39.7 vs 38.0, P = 0.040). Primary outcome: mortality Overall in-hospital mortality was 15.9% (Fig. 1 F). Mortality by TTA showed a modest upward trend: 6 h 20.0% (Table 2, Fig. 2 A; trend P ≈ 0.024). Early vs delayed mortality was 15.3% vs 16.8% (Fig. 2 C). Adjusted logistic regression: OR 1.090 per 1-hour delay (95% CI 0.975–1.217, P = 0.129; Table 3; Fig. 2 B/Fig. 4 “Overall”). Cox model was directionally consistent (HR 1.085; 95% CI 0.986–1.194). Survival analysis Kaplan–Meier curves across TTA strata differed significantly (log-rank P 6 h groups showing the lowest survival (Fig. 3 A). The binary comparison (< 1 h vs ≥ 1 h) was not significant (log-rank Chi2 = 0.72, P = 0.3948; Fig. 3 B), suggesting excess risk is concentrated in the more extreme delays. Subgroups and centers Prespecified subgroups (EOS/LOS, gestational age strata, severity strata) showed ORs crossing 1 with no significant interactions (Fig. 4 ; Table 4). High-severity infants trended toward higher risk (OR 1.26; 95% CI 0.98–1.62). Center-level TTA medians ranged ~ 0.6–1.0 h with mean differences < 0.5 h; mortality ranged roughly 13–18% without a clear center effect (Fig. 6 ). Secondary outcomes Hospital length of stay increased slightly with delay; regression from the analytic code estimated ~ 0.38 additional days per 1-hour delay (Fig. 5 A). Mechanical ventilation duration showed minimal differences across TTA strata (mostly within ~ 2 days; Fig. 5 B). Secondary infection peaked in the 2–3 h group (~ 14%) but the trend test was nonsignificant (P ≈ 0.39; Fig. 5 C). Composite adverse outcome rates were 34–39% across strata with no significant linear trend (P ≈ 0.50; Fig. 5 D). Temporal trends and sensitivity analyses After 2020, TTA decreased and remained near or below the 1-hour target (mean ~ 0.9 h from 2021 onward; Fig. 7 A), whereas mortality fluctuated between ~ 10–20% without a monotonic trend (Fig. 7 B). Sensitivity analyses (culture-positive only, excluding extremely preterm, EOS-only, and period-specific 2018–2020 vs 2021–2023) were consistent with the primary analysis: OR range 1.072–1.135, none statistically significant (Supplementary Table). Discussion In this multicenter cohort of 1,500 neonates with clinically diagnosed sepsis, we observed a modest but consistent directional association between longer time-to-antibiotic administration and worse outcomes, particularly mortality and hospital length of stay. While unadjusted analyses demonstrated an increasing mortality trend across TTA strata, multivariable models adjusting for gestational age, illness severity, comorbidities, and microbiological factors did not show a statistically significant increase in mortality per 1-hour delay. These findings suggest that, in contemporary neonatal practice, modest delays beyond the first hour may confer incremental risk, but that excess mortality is concentrated among infants experiencing more pronounced delays rather than those marginally exceeding the 1-hour benchmark. Our results align with and extend prior neonatal studies reporting attenuated or non-significant associations between antibiotic timing and mortality after adjustment for severity of illness[ 3 , 23 , 24 ]. In contrast to adult sepsis, where each hour of delay has been associated with a clear stepwise increase in mortality [ 1 , 25 , 26 ], neonatal outcomes appear more sensitive to baseline vulnerability and disease phenotype. The slightly higher severity scores observed in the early-treatment group in our cohort further underscore the complexity of confounding by indication: sicker infants may receive antibiotics earlier, potentially biasing unadjusted comparisons toward the null or even reversal of effect. Importantly, survival analyses revealed significant differences across finer TTA categories, whereas the binary comparison of < 1 hour versus ≥ 1 hour did not. This pattern suggests a non-linear relationship in which extreme delays—particularly beyond 2–3 hours or more than 6 hours—are associated with poorer survival, while smaller deviations around the 1-hour threshold may be clinically less consequential. Such findings challenge the rigid application of adult-derived performance metrics to neonatal care and support a more nuanced interpretation of timing targets [ 27 , 28 ]. Subgroup analyses did not identify statistically significant effect modification by EOS versus LOS, gestational age strata, or illness severity, although point estimates suggested higher risk among infants with greater baseline severity. The lack of significant interactions may reflect limited power within subgroups or genuine homogeneity of effect across these dimensions. Nevertheless, the directionally consistent findings across sensitivity analyses—including culture-positive cases and exclusion of extremely preterm infants—enhance the robustness of our conclusions. With respect to secondary outcomes, longer TTA was associated with a small but measurable increase in hospital length of stay, translating to approximately 0.4 additional days per hour of delay. This finding is clinically relevant at a population level and suggests that delayed therapy may prolong recovery even when mortality differences are modest. In contrast, mechanical ventilation duration, secondary infection rates, and composite adverse outcomes did not demonstrate clear linear associations with TTA, indicating that antibiotic timing alone is unlikely to be the dominant driver of these complex outcomes. Temporal analyses showed progressive improvement in antibiotic timeliness after 2020, with mean TTA consistently near or below 1 hour in later years. Notably, this improvement was not accompanied by a parallel monotonic decline in mortality, further reinforcing the notion that outcomes in neonatal sepsis are multifactorial and influenced by advances in supportive care, infection prevention, and case mix [ 29 – 31 ]. These observations caution against overinterpreting antibiotic timing as a singular quality metric without consideration of broader clinical context. Several limitations merit consideration. First, the retrospective observational design precludes causal inference, and residual confounding—particularly related to unmeasured aspects of clinical decision-making—cannot be excluded. Second, TTA was derived from registry timestamps and may be subject to measurement error, although standardized data collection across centers mitigates this concern. Third, while the multicenter nature enhances generalizability, participating centers were all tertiary units, and findings may not extend to lower-resource settings. Finally, we did not adjust for multiple comparisons, and secondary and subgroup analyses should be interpreted as exploratory. Despite these limitations, our study has notable strengths, including its large sample size, inclusion of both EOS and LOS, granular modeling of TTA as a continuous and categorical exposure, and comprehensive sensitivity analyses. Collectively, the findings suggest that while prompt antibiotic administration remains a cornerstone of neonatal sepsis management, strict adherence to a universal 1-hour threshold may oversimplify a more complex risk landscape. Efforts to minimize extreme delays appear particularly important, whereas marginal delays beyond 1 hour may have limited independent impact after accounting for illness severity. Future research should prioritize prospective studies and pragmatic trials to better delineate optimal timing strategies tailored to neonatal risk profiles. Integration of antibiotic timing with severity-adjusted decision support tools may offer a more balanced approach, aligning the urgency of treatment with the imperative to avoid unnecessary antibiotic exposure. In the interim, our findings support continued emphasis on timely therapy while encouraging flexibility and clinical judgment in the application of time-based benchmarks for neonatal sepsis. Conclusion In a large multicenter cohort of neonates with sepsis, we found that delays in antibiotic initiation were associated with modest increases in mortality and hospital length of stay, although the independent effect of incremental delays was attenuated after adjustment for illness severity and perinatal factors. Survival differences were evident across detailed time-to-antibiotic categories, whereas a simple dichotomization at the 1-hour threshold did not distinguish outcomes. These results indicate that the clinical impact of antibiotic timing in neonatal sepsis is non-linear, with greater risk associated with more substantial delays. Strategies aimed at preventing extreme delays, rather than rigid enforcement of a universal timing cutoff, may better align quality metrics with the complex clinical realities of neonatal sepsis. Declarations Conflicts of Interest The authors declared that they have no conflicts of interest regarding this work. Ethics approval and consent to participate This study was conducted in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of Longyan First Affiliated Hospital of Fujian Medical University (approval number: [2024-ETH-017]) and the institutional review boards of all participating centers. Because this was a retrospective analysis of anonymized data from a routinely collected registry, the requirement for written informed consent was waived by the approving committees. Funding Sponsored by Longyan City Science and Technology Plan Project (2024LYF17064) Author Contribution Weixiao Hu: Conceptualization, Methodology, Writing - Original Draft, Investigation, Data Curation, Formal Analysis.Zhenhai Qiu: Investigation, Resources, Validation.Dachun Wang: Visualization, Software, Formal Analysis.Li Zhang: Writing - Review & Editing, Investigation.Jie Tong: Writing - Review & Editing, Supervision, Funding Acquisition. Data Availability The data used to support the findings of this study are available from the corresponding author upon request. References M. A. Glaser, L. M. Hughes, A. Jnah et al. , Neonatal Sepsis: A Review of Pathophysiology and Current Management Strategies. Adv Neonatal Care 21, 49–60 (2021).doi: 10.1097/anc.0000000000000769 . J. Verma, M. J. Sankar, K. Atmakuri et al. , Gut microbiome dysbiosis in neonatal sepsis. Prog Mol Biol Transl Sci 192, 125–147 (2022).doi: 10.1016/bs.pmbts.2022.07.010 . S. A. Coggins, B. Laskin, M. C. Harris et al. , Acute Kidney Injury Associated with Late-Onset Neonatal Sepsis: A Matched Cohort Study. J Pediatr 231, 185–192.e184 (2021).doi: 10.1016/j.jpeds.2020.12.023 . B. T. Oyato, T. K. Sime, T. Debele et al. , Time to recovery of neonatal sepsis and its predictors in public hospitals of North Shoa Zone, Central Ethiopia. BMC Infect Dis 25, 113 (2025).doi: 10.1186/s12879-025-10525-1 . M. P. Menegolla, R. C. Silveira, A. R. H. Görgen et al. , Empiric Antibiotic Therapy and Neurodevelopment Outcome of Very Low Birth Weight Infants. Neuropediatrics 56, 320–327 (2025).doi: 10.1055/a-2561-8208 . E. Pace, T. Yanowitz, Infections in the NICU: Neonatal sepsis. Semin Pediatr Surg 31, 151200 (2022).doi: 10.1016/j.sempedsurg.2022.151200 . M. Tas, C. Turkyilmaz, G. Bozdayi et al. , Case Report: An Unexpected Herbaspirillum Huttiense Bacteremia in the Neonatal Intensive Care Unit. Z Geburtshilfe Neonatol 229, 299–301 (2025).doi: 10.1055/a-2561-0748 . F. Denorme, J. L. Rustad, I. Portier et al. , Neutrophil extracellular trap inhibition improves survival in neonatal mouse infectious peritonitis. Pediatr Res 93, 862–869 (2023).doi: 10.1038/s41390-022-02219-0 . S. L. Holgate, A. Bekker, V. Pillay-Fuentes Lorente et al. , Errors in Antimicrobial Prescription and Administration in Very Low Birth Weight Neonates at a Tertiary South African Hospital. Front Pediatr 10, 838153 (2022).doi: 10.3389/fped.2022.838153 . E. Hegamyer, N. Smith, A. D. Thompson et al. , Treatment of suspected sepsis and septic shock in children with chronic disease seen in the pediatric emergency department. Am J Emerg Med 44, 56–61 (2021).doi: 10.1016/j.ajem.2021.01.026 . S. Gorantiwar, K. de Waal, Progression from sepsis to septic shock and time to treatments in preterm infants with late-onset sepsis. J Paediatr Child Health 57, 1905–1911 (2021).doi: 10.1111/jpc.15606 . V. Spaggiari, E. Passini, S. Crestani et al. , Neonatal septic shock, a focus on first line interventions. Acta Biomed 93, e2022141 (2022).doi: 10.23750/abm.v93i3.12577 . R. Abu Shqara, L. Lowenstein, M. Frank Wolf, Time Matters: Evaluating the Clinical and Infectious Outcomes in Rupture of Membranes <12 Hours versus 12–18 Hours, at Term: A Retrospective Study. Gynecol Obstet Invest , 1–10 (2025).doi: 10.1159/000548662. C. Ma, G. Levin, S. K. Panda et al. , Improving timing of antibiotics in neonates with early onset sepsis - Quality improvement project. J Neonatal Perinatal Med 13, 239–246 (2020).doi: 10.3233/npm-190293 . S. Zeng, Y. Liu, M. Chen et al. , Timing of Intravenous Prophylactic Antibiotic Agents for Cesarean Delivery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Surg Infect (Larchmt) 24, 303–310 (2023).doi: 10.1089/sur.2022.389 . A. Forget, C. Adegboye, M. Alfieri et al. , A sepsis trigger tool reduces time to antibiotic administration in the NICU. J Perinatol 43, 806–812 (2023).doi: 10.1038/s41372-023-01636-1 . A. Khosrojerdi, S. Soudi, A. Z. Hosseini et al. , Immunomodulatory and Therapeutic Effects of Mesenchymal Stem Cells on Organ Dysfunction in Sepsis. Shock 55, 423–440 (2021).doi: 10.1097/shk.0000000000001644 . H. Attia Hussein Mahmoud, R. Parekh, S. Dhandibhotla et al. , Insight Into Neonatal Sepsis: An Overview. Cureus 15, e45530 (2023).doi: 10.7759/cureus.45530 . M. Baczynski, A. Kharrat, F. Zhu et al. , Factors associated with antibiotic administration delay among preterm infants with late-onset bloodstream infection. J Hosp Infect 120, 31–35 (2022).doi: 10.1016/j.jhin.2021.09.026 . M. F. Ricci, P. S. Shah, D. Moddemann et al. , Neurodevelopmental Outcomes of Infants at < 29 Weeks of Gestation Born in Canada Between 2009 and 2016. J Pediatr 247, 60–66.e61 (2022).doi: 10.1016/j.jpeds.2022.04.048 . D. Seyhanlı, T. Gökmen Yıldırım, O. H. Kalkanlı et al. , Prediction model for early diagnosis of late-onset sepsis in preterm newborns. J Neonatal Perinatal Med 17, 661–671 (2024).doi: 10.3233/npm-240011 . O. Okafor, N. Roos, A. A. Abdosh et al. , International virtual confidential reviews of infection-related maternal deaths and near-miss in 11 low- and middle-income countries - case report series and suggested actions. BMC Pregnancy Childbirth 22, 431 (2022).doi: 10.1186/s12884-022-04731-x . H. Shabaninejad, R. P. Kenny, T. Robinson et al. , Genedrive kit for detecting single nucleotide polymorphism m.1555A > G in neonates and their mothers: a systematic review and cost-effectiveness analysis. Health Technol Assess 28, 1–75 (2024).doi: 10.3310/tgac4201 . C. N. Songer, G. S. Calip, N. Srinivasan et al. , Factors influencing antibiotic duration in culture-negative neonatal early-onset sepsis. Pharmacotherapy 41, 148–161 (2021).doi: 10.1002/phar.2507 . A. Dev, M. Casseus, W. J. Baptiste et al. , Neonatal mortality in a public referral hospital in southern Haiti: a retrospective cohort study. BMC Pediatr 22, 81 (2022).doi: 10.1186/s12887-022-03141-4 . O. D. Karla, J. J. Rodolfo Norberto, A. R. Martha et al. , 30-d mortality risk factors in paediatric patients with bloodstream infection due to Enterobacterales: A retrospective observational cohort study. J Glob Antimicrob Resist 45, 299–304 (2025).doi: 10.1016/j.jgar.2025.09.014 . M. B. Dhudasia, W. E. Benitz, D. D. Flannery et al. , Diagnostic Performance and Patient Outcomes With C-Reactive Protein Use in Early-Onset Sepsis Evaluations. J Pediatr 256, 98–104.e106 (2023).doi: 10.1016/j.jpeds.2022.12.007 . Z. V. Mwanza, B. S. White, P. N. Britton et al. , Timing of antibiotics in febrile children meeting sepsis criteria at a paediatric emergency department. Emerg Med Australas 35, 855–861 (2023).doi: 10.1111/1742-6723.14288 . M. Yanni, M. Stark, L. Francis et al. , Neonatal Group B Streptococcal Infection in Australia: A Case-control Study. Pediatr Infect Dis J 42, 429–435 (2023).doi: 10.1097/inf.0000000000003881 . A. Dakin, W. Ferguson, R. Drew et al. , Assessing standards for prevention of early onset group B streptococcal (GBS) disease in Ireland. Ir J Med Sci 191, 785–791 (2022).doi: 10.1007/s11845-021-02639-7 . J. R. Millar, A. Anglemyer, A. Werno et al. , Epidemiology of Infant Group B Streptococcus Infection in New Zealand: A 10-Year Retrospective Study. Pediatr Infect Dis J 44, 1209–1215 (2025).doi: 10.1097/inf.0000000000004908 . Tables Tables are available in the Supplementary Files section. Additional Declarations No competing interests reported. Supplementary Files supptable1pathogens.csv supptable2sensitivity.csv table1baselinecharacteristics.csv table2mortalitybytime.csv table3multivariateregression.csv table4subgroupanalysis.csv Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 08 May, 2026 Reviewers agreed at journal 20 Apr, 2026 Reviewers agreed at journal 19 Apr, 2026 Reviewers agreed at journal 18 Apr, 2026 Reviewers invited by journal 17 Apr, 2026 Editor assigned by journal 19 Mar, 2026 Submission checks completed at journal 19 Mar, 2026 First submitted to journal 17 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9153479","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":627121669,"identity":"f1bdcd03-0b84-4209-8060-01ba33f2e6d3","order_by":0,"name":"Weixiao Hu","email":"","orcid":"","institution":"Longyan First Affiliated Hospital of Fujian Medical University","correspondingAuthor":false,"prefix":"","firstName":"Weixiao","middleName":"","lastName":"Hu","suffix":""},{"id":627121676,"identity":"f660519e-b26d-44f0-9b13-6cb950b4f437","order_by":1,"name":"Zhenhai Qiu","email":"","orcid":"","institution":"Longyan First Affiliated Hospital of Fujian Medical University","correspondingAuthor":false,"prefix":"","firstName":"Zhenhai","middleName":"","lastName":"Qiu","suffix":""},{"id":627121677,"identity":"e2190a1d-cb70-40e3-bb99-b8607099fd7d","order_by":2,"name":"Dachun Wang","email":"","orcid":"","institution":"Longyan First Affiliated Hospital of Fujian Medical University","correspondingAuthor":false,"prefix":"","firstName":"Dachun","middleName":"","lastName":"Wang","suffix":""},{"id":627121679,"identity":"483c68c9-e415-4d45-858e-4a8772cd46c3","order_by":3,"name":"Li Zhang","email":"","orcid":"","institution":"Longyan First Affiliated Hospital of Fujian Medical University","correspondingAuthor":false,"prefix":"","firstName":"Li","middleName":"","lastName":"Zhang","suffix":""},{"id":627121681,"identity":"967e84ce-f6cf-4440-a82c-280bb68c9544","order_by":4,"name":"Jie Tong","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAtUlEQVRIiWNgGAWjYDAC9uaDDz4Y2PDw8zcQq4XnWLLhjIo0GckZB4jVIpFjJs1z5rCNQUMCkToMDiSYSfO2necxYDjA+OFjDlFaDiRbzm27zWPO3MAsOXMbEVrMDjYcvPEWqMWy4QAbMy9RWg4zNkjwtp3jAbqQWC3HmJkkec4cIEGL/Rk2ZmAgJ/NIzjjYTJxfJOe//wiMSjt7fv7mgx8+EqMFCTA2kKZ+FIyCUTAKRgFuAAD+EzpzM8WW/AAAAABJRU5ErkJggg==","orcid":"","institution":"Longyan First Affiliated Hospital of Fujian Medical University","correspondingAuthor":true,"prefix":"","firstName":"Jie","middleName":"","lastName":"Tong","suffix":""}],"badges":[],"createdAt":"2026-03-18 02:08:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9153479/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9153479/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107916167,"identity":"6997ab0e-10c2-4464-8453-82adc77a12c3","added_by":"auto","created_at":"2026-04-27 14:13:12","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":505190,"visible":true,"origin":"","legend":"\u003cp\u003eStudy population characteristics and distribution of time-to-antibiotic administration (A–F: center distribution, gestational age, birth weight, time-to-antibiotic density, sepsis type, overall mortality)\u003c/p\u003e","description":"","filename":"fig1baselinecharacteristics.png","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/88ca1f1a40e5dadf79acb88c.png"},{"id":107916164,"identity":"0783e796-cd65-4a83-8bf0-25b291759ec8","added_by":"auto","created_at":"2026-04-27 14:13:12","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":218759,"visible":true,"origin":"","legend":"\u003cp\u003eAssociation between time-to-antibiotic administration and in-hospital mortality (A) Mortality by TTA categories; (B) adjusted odds ratio per 1-hour delay; (C) early (\u0026lt;1 h) versus delayed (≥1 h) comparison\u003c/p\u003e","description":"","filename":"fig2timemortalityrelationship.png","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/1edd1faa0683d69444ad3bb4.png"},{"id":108007363,"identity":"c8fba857-747a-4e6e-bfaa-805937b332b9","added_by":"auto","created_at":"2026-04-28 12:59:40","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":296776,"visible":true,"origin":"","legend":"\u003cp\u003eKaplan–Meier survival curves stratified by time-to-antibiotic administration (A) Multiple TTA categories; (B) early (\u0026lt;1 h) versus delayed (≥1 h) administration\u003c/p\u003e","description":"","filename":"fig3kaplanmeier.png","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/8038a476376b4d991fa54f08.png"},{"id":107916175,"identity":"66f01874-8579-4098-b716-7e08edb515bc","added_by":"auto","created_at":"2026-04-27 14:13:13","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":296552,"visible":true,"origin":"","legend":"\u003cp\u003eAdjusted associations between time-to-antibiotic delay and mortality across prespecified subgroups and overall population\u003c/p\u003e","description":"","filename":"fig4forestplot.png","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/b5de45d51489a8bd92193794.png"},{"id":107916171,"identity":"3852ed71-4ab5-4b47-9581-b065d7315439","added_by":"auto","created_at":"2026-04-27 14:13:12","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":296814,"visible":true,"origin":"","legend":"\u003cp\u003eSecondary outcomes according to time-to-antibiotic categories (A) Hospital length of stay; (B) duration of mechanical ventilation; (C) secondary infection; (D) composite adverse outcome\u003c/p\u003e","description":"","filename":"fig5secondaryoutcomes.png","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/d691fa19b14116824a23683d.png"},{"id":107916169,"identity":"a3fc0e2e-3403-41e0-a2f5-5eea18157e04","added_by":"auto","created_at":"2026-04-27 14:13:12","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":143051,"visible":true,"origin":"","legend":"\u003cp\u003eCenter-level variation in time-to-antibiotic administration and in-hospital mortality\u003c/p\u003e","description":"","filename":"fig6centercomparison.png","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/38ecbe19e1a7d60e59fcc5a4.png"},{"id":107916170,"identity":"6941e28d-d7c5-4cd8-891d-03f528e5ee4a","added_by":"auto","created_at":"2026-04-27 14:13:12","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":327839,"visible":true,"origin":"","legend":"\u003cp\u003eTemporal trends in time-to-antibiotic administration and in-hospital mortality from 2018 to 2023\u003c/p\u003e","description":"","filename":"fig7timetrend.png","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/834491432341bfbed6b7d1d2.png"},{"id":108008919,"identity":"7a824b05-b418-4119-bece-2668531da461","added_by":"auto","created_at":"2026-04-28 13:08:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2285612,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/f112f48d-2bd0-4965-8dad-f3614e8ea0b0.pdf"},{"id":108006675,"identity":"b7616873-5b57-42c3-a409-a037e9720063","added_by":"auto","created_at":"2026-04-28 12:56:24","extension":"csv","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":396,"visible":true,"origin":"","legend":"","description":"","filename":"supptable1pathogens.csv","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/20125031d3f85aa0ddcb009d.csv"},{"id":107916178,"identity":"6168c3e3-d75e-43d5-a01c-161130109468","added_by":"auto","created_at":"2026-04-27 14:13:13","extension":"csv","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":301,"visible":true,"origin":"","legend":"","description":"","filename":"supptable2sensitivity.csv","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/8aa11c374ae00d962b54fee6.csv"},{"id":107916162,"identity":"3ac16ad1-5c9d-4945-b5da-88d87126b62d","added_by":"auto","created_at":"2026-04-27 14:13:12","extension":"csv","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":1326,"visible":true,"origin":"","legend":"","description":"","filename":"table1baselinecharacteristics.csv","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/e9e05d3e8888e362dc279250.csv"},{"id":107916174,"identity":"f2383bf0-1974-4869-b4c0-fcd26ec31b2b","added_by":"auto","created_at":"2026-04-27 14:13:12","extension":"csv","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":127,"visible":true,"origin":"","legend":"","description":"","filename":"table2mortalitybytime.csv","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/7bd15718c4305d42727ed6c3.csv"},{"id":108006689,"identity":"3c731f4a-5549-4ec5-b456-4cf9e83e4145","added_by":"auto","created_at":"2026-04-28 12:56:30","extension":"csv","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":760,"visible":true,"origin":"","legend":"","description":"","filename":"table3multivariateregression.csv","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/98dd6977870a0a485f3f46a6.csv"},{"id":108007245,"identity":"5db3ad68-2d97-409e-8e46-f03916384227","added_by":"auto","created_at":"2026-04-28 12:59:09","extension":"csv","order_by":5,"title":"","display":"","copyAsset":false,"role":"supplement","size":511,"visible":true,"origin":"","legend":"","description":"","filename":"table4subgroupanalysis.csv","url":"https://assets-eu.researchsquare.com/files/rs-9153479/v1/c44da3178398c265ce31a98f.csv"}],"financialInterests":"No competing interests reported.","formattedTitle":"Data analysis from the Sepsis Registry study on the association between antibiotic use duration and clinical outcomes in neonatal sepsis","fulltext":[{"header":"Introduction","content":"\u003cp\u003eNeonatal sepsis remains a leading cause of morbidity and mortality worldwide, particularly among preterm and low\u0026ndash;birth weight infants, despite advances in perinatal care and antimicrobial therapy[\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The burden is especially pronounced in low- and middle-income settings, but substantial mortality persists even in high-resource neonatal intensive care units (NICUs) [\u003cspan additionalcitationids=\"CR5\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Early recognition and timely initiation of appropriate antimicrobial therapy are therefore central components of neonatal sepsis management and are emphasized across international guidelines[\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn adult and pediatric populations, a robust body of evidence supports the concept that delays in antibiotic administration are associated with increased mortality in sepsis and septic shock [\u003cspan additionalcitationids=\"CR11\" citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. This evidence has driven the widespread adoption of time-based performance metrics, most notably the \u0026ldquo;1-hour bundle,\u0026rdquo; which prioritizes prompt antibiotic delivery following sepsis recognition [\u003cspan additionalcitationids=\"CR14 CR15\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. However, extrapolation of these findings to neonates is not straightforward. Neonatal sepsis differs fundamentally in its pathophysiology, clinical presentation, pathogen spectrum, and host immune response, and neonates are uniquely vulnerable to both undertreatment and overtreatment with antibiotics [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eExisting evidence on the relationship between time-to-antibiotic (TTA) administration and outcomes in neonatal sepsis is limited and inconsistent. Several single-center studies and secondary analyses suggest potential harm associated with prolonged delays, particularly in critically ill or extremely preterm infants [\u003cspan additionalcitationids=\"CR20\" citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In contrast, other investigations have reported weak or non-significant associations once illness severity and perinatal factors are accounted for, raising questions about whether a universal 1-hour threshold is appropriate for all neonatal populations[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Importantly, most prior studies have been constrained by small sample sizes, heterogeneous definitions of exposure, limited adjustment for confounding, or binary categorizations of TTA that may obscure non-linear risk patterns.\u003c/p\u003e \u003cp\u003eMoreover, neonatal sepsis encompasses both early-onset sepsis (EOS), typically related to perinatal transmission, and late-onset sepsis (LOS), often associated with nosocomial or community-acquired pathogens. These entities differ in timing, microbiology, and clinical trajectory, yet are frequently pooled in analyses without formal interaction testing [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. Multicenter data capturing contemporary practice patterns, center-level variation, and detailed timing of antibiotic initiation remain scarce.\u003c/p\u003e \u003cp\u003eTo address these gaps, we conducted a large multicenter retrospective cohort study using a standardized neonatal sepsis registry from five centers over a six-year period. Our objectives were to (1) characterize the distribution of TTA in routine clinical practice, (2) examine the association between incremental delays in antibiotic administration and in-hospital mortality using both continuous and categorical exposure definitions, and (3) explore potential effect modification across clinically relevant subgroups, including EOS versus LOS, gestational age, and illness severity. We further evaluated secondary outcomes related to healthcare utilization and complications to provide a comprehensive assessment of the clinical impact of antibiotic timing in neonatal sepsis.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and data source\u003c/h2\u003e \u003cp\u003eThis was a multicenter retrospective cohort study using the Sepsis Registry from five centers between January 2018 and December 2023, including hospitalized neonates with clinically diagnosed sepsis.\u003c/p\u003e \u003cp\u003eData extraction captured demographics, clinical variables, treatments, and outcomes from the registry; analysis followed a prespecified statistical plan.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePopulation and eligibility\u003c/h3\u003e\n\u003cp\u003eWe included 1,500 neonates with sepsis who received intravenous antibiotics and had documented time-to-antibiotic (TTA).\u003c/p\u003e \u003cp\u003eKey exclusions in the registry preprocessing were missing TTA, missing survival outcome, or duplicate encounters. Early-onset sepsis (EOS) and late-onset sepsis (LOS) were both retained (EOS 56.8%, LOS 43.2%).\u003c/p\u003e\n\u003ch3\u003eExposure definition\u003c/h3\u003e\n\u003cp\u003eThe main exposure was TTA, defined as hours from admission/diagnosis to first intravenous antibiotic dose, treated as a continuous variable and categorized as \u0026lt;\u0026thinsp;1 h, 1\u0026ndash;2 h, 2\u0026ndash;3 h, 3\u0026ndash;6 h, and \u0026gt;\u0026thinsp;6 h.\u003c/p\u003e \u003cp\u003eA binary comparison of early (\u0026lt;\u0026thinsp;1 h) versus delayed (\u0026ge;\u0026thinsp;1 h) administration was also examined.\u003c/p\u003e\n\u003ch3\u003eOutcomes\u003c/h3\u003e\n\u003cp\u003ePrimary outcome: in-hospital mortality.\u003c/p\u003e \u003cp\u003eSecondary outcomes: hospital length of stay (LOS), mechanical ventilation duration, secondary infection, and a composite adverse outcome (per study plan).\u003c/p\u003e\n\u003ch3\u003eCovariates\u003c/h3\u003e\n\u003cp\u003ePrespecified covariates: gestational age, birth weight, 5-minute Apgar score, illness severity score, sepsis type (EOS/LOS), respiratory distress syndrome (RDS), necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), blood culture positivity, and major pathogen category.\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eBaseline characteristics were summarized overall and by early vs delayed groups; group differences used appropriate univariable tests (Table\u0026nbsp;1, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eMortality was described across TTA strata with trend testing (Table\u0026nbsp;2, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA) and binary early vs delayed comparison (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eMultivariable logistic regression estimated the adjusted odds ratio (OR) for mortality per 1-hour delay, adjusting for the prespecified covariates (Table\u0026nbsp;3, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB/Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e \u0026ldquo;Overall\u0026rdquo;).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eCox proportional hazards models estimated hazard ratios (HR) for time-to-event mortality; Kaplan\u0026ndash;Meier curves with log-rank tests compared survival across TTA strata and by \u0026lt;\u0026thinsp;1 h vs\u0026thinsp;\u0026ge;\u0026thinsp;1 h (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSubgroup analyses were predefined (EOS/LOS, gestational age strata, severity strata) with interaction assessment; center-level comparisons were descriptive (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSensitivity analyses: culture-positive only, excluding extremely preterm, EOS-only, and period-specific analyses (2018\u0026ndash;2020 vs 2021\u0026ndash;2023) (Supplementary Table).\u003c/p\u003e \u003cp\u003eSecondary outcomes were compared across TTA categories with trend tests (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003e). Two-sided P\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicated statistical significance. Analyses were performed per the prespecified plan; no multiplicity adjustments were applied.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003eStudy population and baseline characteristics\u003c/h2\u003e \u003cp\u003eWe analyzed 1,500 neonates (5 centers). Median gestational age was 35.0 weeks (IQR 32.3\u0026ndash;37.6), median birth weight 3,486 g; 55.1% were male. EOS accounted for 56.8%, and blood cultures were positive in 64.1% (Table\u0026nbsp;1, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA\u0026ndash;F).\u003c/p\u003e \u003cp\u003eMedian TTA was 0.76 hours; 58.0% received antibiotics within 1 hour and 91.2% within 3 hours (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC). Early (\u0026lt;\u0026thinsp;1 h) and delayed (\u0026ge;\u0026thinsp;1 h) groups had similar gestational age and birth weight; the early group showed slightly higher severity scores (median 39.7 vs 38.0, P\u0026thinsp;=\u0026thinsp;0.040).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003ePrimary outcome: mortality\u003c/h2\u003e \u003cp\u003eOverall in-hospital mortality was 15.9% (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eF). Mortality by TTA showed a modest upward trend: \u0026lt;1 h 15.3%, 1\u0026ndash;2 h 16.2%, 2\u0026ndash;3 h 18.9%, 3\u0026ndash;6 h 16.2%, \u0026gt;\u0026thinsp;6 h 20.0% (Table\u0026nbsp;2, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA; trend P\u0026thinsp;\u0026asymp;\u0026thinsp;0.024). Early vs delayed mortality was 15.3% vs 16.8% (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC).\u003c/p\u003e \u003cp\u003eAdjusted logistic regression: OR 1.090 per 1-hour delay (95% CI 0.975\u0026ndash;1.217, P\u0026thinsp;=\u0026thinsp;0.129; Table\u0026nbsp;3; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB/Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e \u0026ldquo;Overall\u0026rdquo;). Cox model was directionally consistent (HR 1.085; 95% CI 0.986\u0026ndash;1.194).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eSurvival analysis\u003c/h2\u003e \u003cp\u003eKaplan\u0026ndash;Meier curves across TTA strata differed significantly (log-rank P\u0026thinsp;\u0026lt;\u0026thinsp;0.001), with 2\u0026ndash;3 h and \u0026gt;\u0026thinsp;6 h groups showing the lowest survival (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003eA).\u003c/p\u003e \u003cp\u003eThe binary comparison (\u0026lt;\u0026thinsp;1 h vs\u0026thinsp;\u0026ge;\u0026thinsp;1 h) was not significant (log-rank Chi2\u0026thinsp;=\u0026thinsp;0.72, P\u0026thinsp;=\u0026thinsp;0.3948; Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003eB), suggesting excess risk is concentrated in the more extreme delays.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eSubgroups and centers\u003c/h2\u003e \u003cp\u003ePrespecified subgroups (EOS/LOS, gestational age strata, severity strata) showed ORs crossing 1 with no significant interactions (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e4\u003c/span\u003e; Table\u0026nbsp;4). High-severity infants trended toward higher risk (OR 1.26; 95% CI 0.98\u0026ndash;1.62).\u003c/p\u003e \u003cp\u003eCenter-level TTA medians ranged\u0026thinsp;~\u0026thinsp;0.6\u0026ndash;1.0 h with mean differences\u0026thinsp;\u0026lt;\u0026thinsp;0.5 h; mortality ranged roughly 13\u0026ndash;18% without a clear center effect (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003eSecondary outcomes\u003c/h2\u003e \u003cp\u003eHospital length of stay increased slightly with delay; regression from the analytic code estimated\u0026thinsp;~\u0026thinsp;0.38 additional days per 1-hour delay (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003eA). Mechanical ventilation duration showed minimal differences across TTA strata (mostly within ~\u0026thinsp;2 days; Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003eSecondary infection peaked in the 2\u0026ndash;3 h group (~\u0026thinsp;14%) but the trend test was nonsignificant (P\u0026thinsp;\u0026asymp;\u0026thinsp;0.39; Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003eC). Composite adverse outcome rates were 34\u0026ndash;39% across strata with no significant linear trend (P\u0026thinsp;\u0026asymp;\u0026thinsp;0.50; Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e5\u003c/span\u003eD).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003eTemporal trends and sensitivity analyses\u003c/h2\u003e \u003cp\u003eAfter 2020, TTA decreased and remained near or below the 1-hour target (mean\u0026thinsp;~\u0026thinsp;0.9 h from 2021 onward; Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eA), whereas mortality fluctuated between ~\u0026thinsp;10\u0026ndash;20% without a monotonic trend (Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003eB).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSensitivity analyses (culture-positive only, excluding extremely preterm, EOS-only, and period-specific 2018\u0026ndash;2020 vs 2021\u0026ndash;2023) were consistent with the primary analysis: OR range 1.072\u0026ndash;1.135, none statistically significant (Supplementary Table).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eIn this multicenter cohort of 1,500 neonates with clinically diagnosed sepsis, we observed a modest but consistent directional association between longer time-to-antibiotic administration and worse outcomes, particularly mortality and hospital length of stay. While unadjusted analyses demonstrated an increasing mortality trend across TTA strata, multivariable models adjusting for gestational age, illness severity, comorbidities, and microbiological factors did not show a statistically significant increase in mortality per 1-hour delay. These findings suggest that, in contemporary neonatal practice, modest delays beyond the first hour may confer incremental risk, but that excess mortality is concentrated among infants experiencing more pronounced delays rather than those marginally exceeding the 1-hour benchmark.\u003c/p\u003e \u003cp\u003eOur results align with and extend prior neonatal studies reporting attenuated or non-significant associations between antibiotic timing and mortality after adjustment for severity of illness[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. In contrast to adult sepsis, where each hour of delay has been associated with a clear stepwise increase in mortality [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e], neonatal outcomes appear more sensitive to baseline vulnerability and disease phenotype. The slightly higher severity scores observed in the early-treatment group in our cohort further underscore the complexity of confounding by indication: sicker infants may receive antibiotics earlier, potentially biasing unadjusted comparisons toward the null or even reversal of effect.\u003c/p\u003e \u003cp\u003eImportantly, survival analyses revealed significant differences across finer TTA categories, whereas the binary comparison of \u0026lt;\u0026thinsp;1 hour versus \u0026ge;\u0026thinsp;1 hour did not. This pattern suggests a non-linear relationship in which extreme delays\u0026mdash;particularly beyond 2\u0026ndash;3 hours or more than 6 hours\u0026mdash;are associated with poorer survival, while smaller deviations around the 1-hour threshold may be clinically less consequential. Such findings challenge the rigid application of adult-derived performance metrics to neonatal care and support a more nuanced interpretation of timing targets [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSubgroup analyses did not identify statistically significant effect modification by EOS versus LOS, gestational age strata, or illness severity, although point estimates suggested higher risk among infants with greater baseline severity. The lack of significant interactions may reflect limited power within subgroups or genuine homogeneity of effect across these dimensions. Nevertheless, the directionally consistent findings across sensitivity analyses\u0026mdash;including culture-positive cases and exclusion of extremely preterm infants\u0026mdash;enhance the robustness of our conclusions.\u003c/p\u003e \u003cp\u003eWith respect to secondary outcomes, longer TTA was associated with a small but measurable increase in hospital length of stay, translating to approximately 0.4 additional days per hour of delay. This finding is clinically relevant at a population level and suggests that delayed therapy may prolong recovery even when mortality differences are modest. In contrast, mechanical ventilation duration, secondary infection rates, and composite adverse outcomes did not demonstrate clear linear associations with TTA, indicating that antibiotic timing alone is unlikely to be the dominant driver of these complex outcomes.\u003c/p\u003e \u003cp\u003eTemporal analyses showed progressive improvement in antibiotic timeliness after 2020, with mean TTA consistently near or below 1 hour in later years. Notably, this improvement was not accompanied by a parallel monotonic decline in mortality, further reinforcing the notion that outcomes in neonatal sepsis are multifactorial and influenced by advances in supportive care, infection prevention, and case mix [\u003cspan additionalcitationids=\"CR30\" citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. These observations caution against overinterpreting antibiotic timing as a singular quality metric without consideration of broader clinical context.\u003c/p\u003e \u003cp\u003eSeveral limitations merit consideration. First, the retrospective observational design precludes causal inference, and residual confounding\u0026mdash;particularly related to unmeasured aspects of clinical decision-making\u0026mdash;cannot be excluded. Second, TTA was derived from registry timestamps and may be subject to measurement error, although standardized data collection across centers mitigates this concern. Third, while the multicenter nature enhances generalizability, participating centers were all tertiary units, and findings may not extend to lower-resource settings. Finally, we did not adjust for multiple comparisons, and secondary and subgroup analyses should be interpreted as exploratory.\u003c/p\u003e \u003cp\u003eDespite these limitations, our study has notable strengths, including its large sample size, inclusion of both EOS and LOS, granular modeling of TTA as a continuous and categorical exposure, and comprehensive sensitivity analyses. Collectively, the findings suggest that while prompt antibiotic administration remains a cornerstone of neonatal sepsis management, strict adherence to a universal 1-hour threshold may oversimplify a more complex risk landscape. Efforts to minimize extreme delays appear particularly important, whereas marginal delays beyond 1 hour may have limited independent impact after accounting for illness severity.\u003c/p\u003e \u003cp\u003eFuture research should prioritize prospective studies and pragmatic trials to better delineate optimal timing strategies tailored to neonatal risk profiles. Integration of antibiotic timing with severity-adjusted decision support tools may offer a more balanced approach, aligning the urgency of treatment with the imperative to avoid unnecessary antibiotic exposure. In the interim, our findings support continued emphasis on timely therapy while encouraging flexibility and clinical judgment in the application of time-based benchmarks for neonatal sepsis.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn a large multicenter cohort of neonates with sepsis, we found that delays in antibiotic initiation were associated with modest increases in mortality and hospital length of stay, although the independent effect of incremental delays was attenuated after adjustment for illness severity and perinatal factors. Survival differences were evident across detailed time-to-antibiotic categories, whereas a simple dichotomization at the 1-hour threshold did not distinguish outcomes. These results indicate that the clinical impact of antibiotic timing in neonatal sepsis is non-linear, with greater risk associated with more substantial delays. Strategies aimed at preventing extreme delays, rather than rigid enforcement of a universal timing cutoff, may better align quality metrics with the complex clinical realities of neonatal sepsis.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eConflicts of Interest\u003c/h2\u003e\n\u003cp\u003eThe authors declared that they have no conflicts of interest regarding this work.\u003c/p\u003e\n\u003ch2\u003eEthics approval and consent to participate\u003c/h2\u003e\n\u003cp\u003eThis study was conducted in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of Longyan First Affiliated Hospital of Fujian Medical University (approval number: [2024-ETH-017]) and the institutional review boards of all participating centers. Because this was a retrospective analysis of anonymized data from a routinely collected registry, the requirement for written informed consent was waived by the approving committees.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eSponsored by Longyan City Science and Technology Plan Project (2024LYF17064)\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eWeixiao Hu: Conceptualization, Methodology, Writing - Original Draft, Investigation, Data Curation, Formal Analysis.Zhenhai Qiu: Investigation, Resources, Validation.Dachun Wang: Visualization, Software, Formal Analysis.Li Zhang: Writing - Review \u0026amp; Editing, Investigation.Jie Tong: Writing - Review \u0026amp; Editing, Supervision, Funding Acquisition.\u003c/p\u003e\n\u003ch2\u003eData Availability\u003c/h2\u003e\n\u003cp\u003eThe data used to support the findings of this study are available from the corresponding author upon request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eM. A. Glaser, L. M. Hughes, A. Jnah \u003cem\u003eet al.\u003c/em\u003e, Neonatal Sepsis: A Review of Pathophysiology and Current Management Strategies. \u003cem\u003eAdv Neonatal Care\u003c/em\u003e 21, 49\u0026ndash;60 (2021).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/anc.0000000000000769\u003c/span\u003e\u003cspan address=\"10.1097/anc.0000000000000769\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJ. Verma, M. J. Sankar, K. Atmakuri \u003cem\u003eet al.\u003c/em\u003e, Gut microbiome dysbiosis in neonatal sepsis. \u003cem\u003eProg Mol Biol Transl Sci\u003c/em\u003e 192, 125\u0026ndash;147 (2022).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/bs.pmbts.2022.07.010\u003c/span\u003e\u003cspan address=\"10.1016/bs.pmbts.2022.07.010\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eS. A. Coggins, B. Laskin, M. C. Harris \u003cem\u003eet al.\u003c/em\u003e, Acute Kidney Injury Associated with Late-Onset Neonatal Sepsis: A Matched Cohort Study. \u003cem\u003eJ Pediatr\u003c/em\u003e 231, 185\u0026ndash;192.e184 (2021).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jpeds.2020.12.023\u003c/span\u003e\u003cspan address=\"10.1016/j.jpeds.2020.12.023\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eB. T. Oyato, T. K. Sime, T. Debele \u003cem\u003eet al.\u003c/em\u003e, Time to recovery of neonatal sepsis and its predictors in public hospitals of North Shoa Zone, Central Ethiopia. \u003cem\u003eBMC Infect Dis\u003c/em\u003e 25, 113 (2025).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12879-025-10525-1\u003c/span\u003e\u003cspan address=\"10.1186/s12879-025-10525-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM. P. Menegolla, R. C. Silveira, A. R. H. G\u0026ouml;rgen \u003cem\u003eet al.\u003c/em\u003e, Empiric Antibiotic Therapy and Neurodevelopment Outcome of Very Low Birth Weight Infants. \u003cem\u003eNeuropediatrics\u003c/em\u003e 56, 320\u0026ndash;327 (2025).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1055/a-2561-8208\u003c/span\u003e\u003cspan address=\"10.1055/a-2561-8208\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eE. Pace, T. Yanowitz, Infections in the NICU: Neonatal sepsis. \u003cem\u003eSemin Pediatr Surg\u003c/em\u003e 31, 151200 (2022).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.sempedsurg.2022.151200\u003c/span\u003e\u003cspan address=\"10.1016/j.sempedsurg.2022.151200\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM. Tas, C. Turkyilmaz, G. Bozdayi \u003cem\u003eet al.\u003c/em\u003e, Case Report: An Unexpected Herbaspirillum Huttiense Bacteremia in the Neonatal Intensive Care Unit. \u003cem\u003eZ Geburtshilfe Neonatol\u003c/em\u003e 229, 299\u0026ndash;301 (2025).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1055/a-2561-0748\u003c/span\u003e\u003cspan address=\"10.1055/a-2561-0748\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eF. Denorme, J. L. Rustad, I. Portier \u003cem\u003eet al.\u003c/em\u003e, Neutrophil extracellular trap inhibition improves survival in neonatal mouse infectious peritonitis. \u003cem\u003ePediatr Res\u003c/em\u003e 93, 862\u0026ndash;869 (2023).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41390-022-02219-0\u003c/span\u003e\u003cspan address=\"10.1038/s41390-022-02219-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eS. L. Holgate, A. Bekker, V. Pillay-Fuentes Lorente \u003cem\u003eet al.\u003c/em\u003e, Errors in Antimicrobial Prescription and Administration in Very Low Birth Weight Neonates at a Tertiary South African Hospital. \u003cem\u003eFront Pediatr\u003c/em\u003e 10, 838153 (2022).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fped.2022.838153\u003c/span\u003e\u003cspan address=\"10.3389/fped.2022.838153\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eE. Hegamyer, N. Smith, A. D. Thompson \u003cem\u003eet al.\u003c/em\u003e, Treatment of suspected sepsis and septic shock in children with chronic disease seen in the pediatric emergency department. \u003cem\u003eAm J Emerg Med\u003c/em\u003e 44, 56\u0026ndash;61 (2021).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.ajem.2021.01.026\u003c/span\u003e\u003cspan address=\"10.1016/j.ajem.2021.01.026\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eS. Gorantiwar, K. de Waal, Progression from sepsis to septic shock and time to treatments in preterm infants with late-onset sepsis. \u003cem\u003eJ Paediatr Child Health\u003c/em\u003e 57, 1905\u0026ndash;1911 (2021).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/jpc.15606\u003c/span\u003e\u003cspan address=\"10.1111/jpc.15606\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eV. Spaggiari, E. Passini, S. Crestani \u003cem\u003eet al.\u003c/em\u003e, Neonatal septic shock, a focus on first line interventions. \u003cem\u003eActa Biomed\u003c/em\u003e 93, e2022141 (2022).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.23750/abm.v93i3.12577\u003c/span\u003e\u003cspan address=\"10.23750/abm.v93i3.12577\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eR. Abu Shqara, L. Lowenstein, M. Frank Wolf, Time Matters: Evaluating the Clinical and Infectious Outcomes in Rupture of Membranes \u0026lt;12 Hours versus 12\u0026ndash;18 Hours, at Term: A Retrospective Study. \u003cem\u003eGynecol Obstet Invest\u003c/em\u003e, 1\u0026ndash;10 (2025).doi: 10.1159/000548662.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eC. Ma, G. Levin, S. K. Panda \u003cem\u003eet al.\u003c/em\u003e, Improving timing of antibiotics in neonates with early onset sepsis - Quality improvement project. \u003cem\u003eJ Neonatal Perinatal Med\u003c/em\u003e 13, 239\u0026ndash;246 (2020).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3233/npm-190293\u003c/span\u003e\u003cspan address=\"10.3233/npm-190293\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eS. Zeng, Y. Liu, M. Chen \u003cem\u003eet al.\u003c/em\u003e, Timing of Intravenous Prophylactic Antibiotic Agents for Cesarean Delivery: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. \u003cem\u003eSurg Infect (Larchmt)\u003c/em\u003e 24, 303\u0026ndash;310 (2023).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1089/sur.2022.389\u003c/span\u003e\u003cspan address=\"10.1089/sur.2022.389\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eA. Forget, C. Adegboye, M. Alfieri \u003cem\u003eet al.\u003c/em\u003e, A sepsis trigger tool reduces time to antibiotic administration in the NICU. \u003cem\u003eJ Perinatol\u003c/em\u003e 43, 806\u0026ndash;812 (2023).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/s41372-023-01636-1\u003c/span\u003e\u003cspan address=\"10.1038/s41372-023-01636-1\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eA. Khosrojerdi, S. Soudi, A. Z. Hosseini \u003cem\u003eet al.\u003c/em\u003e, Immunomodulatory and Therapeutic Effects of Mesenchymal Stem Cells on Organ Dysfunction in Sepsis. \u003cem\u003eShock\u003c/em\u003e 55, 423\u0026ndash;440 (2021).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/shk.0000000000001644\u003c/span\u003e\u003cspan address=\"10.1097/shk.0000000000001644\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eH. Attia Hussein Mahmoud, R. Parekh, S. Dhandibhotla \u003cem\u003eet al.\u003c/em\u003e, Insight Into Neonatal Sepsis: An Overview. \u003cem\u003eCureus\u003c/em\u003e 15, e45530 (2023).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.7759/cureus.45530\u003c/span\u003e\u003cspan address=\"10.7759/cureus.45530\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM. Baczynski, A. Kharrat, F. Zhu \u003cem\u003eet al.\u003c/em\u003e, Factors associated with antibiotic administration delay among preterm infants with late-onset bloodstream infection. \u003cem\u003eJ Hosp Infect\u003c/em\u003e 120, 31\u0026ndash;35 (2022).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jhin.2021.09.026\u003c/span\u003e\u003cspan address=\"10.1016/j.jhin.2021.09.026\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM. F. Ricci, P. S. Shah, D. Moddemann \u003cem\u003eet al.\u003c/em\u003e, Neurodevelopmental Outcomes of Infants at \u0026lt;\u0026thinsp;29 Weeks of Gestation Born in Canada Between 2009 and 2016. \u003cem\u003eJ Pediatr\u003c/em\u003e 247, 60\u0026ndash;66.e61 (2022).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jpeds.2022.04.048\u003c/span\u003e\u003cspan address=\"10.1016/j.jpeds.2022.04.048\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eD. Seyhanlı, T. G\u0026ouml;kmen Yıldırım, O. H. Kalkanlı \u003cem\u003eet al.\u003c/em\u003e, Prediction model for early diagnosis of late-onset sepsis in preterm newborns. \u003cem\u003eJ Neonatal Perinatal Med\u003c/em\u003e 17, 661\u0026ndash;671 (2024).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3233/npm-240011\u003c/span\u003e\u003cspan address=\"10.3233/npm-240011\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eO. Okafor, N. Roos, A. A. Abdosh \u003cem\u003eet al.\u003c/em\u003e, International virtual confidential reviews of infection-related maternal deaths and near-miss in 11 low- and middle-income countries - case report series and suggested actions. \u003cem\u003eBMC Pregnancy Childbirth\u003c/em\u003e 22, 431 (2022).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12884-022-04731-x\u003c/span\u003e\u003cspan address=\"10.1186/s12884-022-04731-x\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eH. Shabaninejad, R. P. Kenny, T. Robinson \u003cem\u003eet al.\u003c/em\u003e, Genedrive kit for detecting single nucleotide polymorphism m.1555A\u0026thinsp;\u0026gt;\u0026thinsp;G in neonates and their mothers: a systematic review and cost-effectiveness analysis. \u003cem\u003eHealth Technol Assess\u003c/em\u003e 28, 1\u0026ndash;75 (2024).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3310/tgac4201\u003c/span\u003e\u003cspan address=\"10.3310/tgac4201\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eC. N. Songer, G. S. Calip, N. Srinivasan \u003cem\u003eet al.\u003c/em\u003e, Factors influencing antibiotic duration in culture-negative neonatal early-onset sepsis. \u003cem\u003ePharmacotherapy\u003c/em\u003e 41, 148\u0026ndash;161 (2021).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1002/phar.2507\u003c/span\u003e\u003cspan address=\"10.1002/phar.2507\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eA. Dev, M. Casseus, W. J. Baptiste \u003cem\u003eet al.\u003c/em\u003e, Neonatal mortality in a public referral hospital in southern Haiti: a retrospective cohort study. \u003cem\u003eBMC Pediatr\u003c/em\u003e 22, 81 (2022).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12887-022-03141-4\u003c/span\u003e\u003cspan address=\"10.1186/s12887-022-03141-4\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eO. D. Karla, J. J. Rodolfo Norberto, A. R. Martha \u003cem\u003eet al.\u003c/em\u003e, 30-d mortality risk factors in paediatric patients with bloodstream infection due to Enterobacterales: A retrospective observational cohort study. \u003cem\u003eJ Glob Antimicrob Resist\u003c/em\u003e 45, 299\u0026ndash;304 (2025).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jgar.2025.09.014\u003c/span\u003e\u003cspan address=\"10.1016/j.jgar.2025.09.014\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM. B. Dhudasia, W. E. Benitz, D. D. Flannery \u003cem\u003eet al.\u003c/em\u003e, Diagnostic Performance and Patient Outcomes With C-Reactive Protein Use in Early-Onset Sepsis Evaluations. \u003cem\u003eJ Pediatr\u003c/em\u003e 256, 98\u0026ndash;104.e106 (2023).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jpeds.2022.12.007\u003c/span\u003e\u003cspan address=\"10.1016/j.jpeds.2022.12.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZ. V. Mwanza, B. S. White, P. N. Britton \u003cem\u003eet al.\u003c/em\u003e, Timing of antibiotics in febrile children meeting sepsis criteria at a paediatric emergency department. \u003cem\u003eEmerg Med Australas\u003c/em\u003e 35, 855\u0026ndash;861 (2023).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/1742-6723.14288\u003c/span\u003e\u003cspan address=\"10.1111/1742-6723.14288\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM. Yanni, M. Stark, L. Francis \u003cem\u003eet al.\u003c/em\u003e, Neonatal Group B Streptococcal Infection in Australia: A Case-control Study. \u003cem\u003ePediatr Infect Dis J\u003c/em\u003e 42, 429\u0026ndash;435 (2023).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/inf.0000000000003881\u003c/span\u003e\u003cspan address=\"10.1097/inf.0000000000003881\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eA. Dakin, W. Ferguson, R. Drew \u003cem\u003eet al.\u003c/em\u003e, Assessing standards for prevention of early onset group B streptococcal (GBS) disease in Ireland. \u003cem\u003eIr J Med Sci\u003c/em\u003e 191, 785\u0026ndash;791 (2022).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s11845-021-02639-7\u003c/span\u003e\u003cspan address=\"10.1007/s11845-021-02639-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJ. R. Millar, A. Anglemyer, A. Werno \u003cem\u003eet al.\u003c/em\u003e, Epidemiology of Infant Group B Streptococcus Infection in New Zealand: A 10-Year Retrospective Study. \u003cem\u003ePediatr Infect Dis J\u003c/em\u003e 44, 1209\u0026ndash;1215 (2025).doi: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/inf.0000000000004908\u003c/span\u003e\u003cspan address=\"10.1097/inf.0000000000004908\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables are available in the Supplementary Files section.\u003c/p\u003e\n"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-medical-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejmr","sideBox":"Learn more about [European Journal of Medical Research](http://eurjmedres.biomedcentral.com)","snPcode":"40001","submissionUrl":"https://submission.nature.com/new-submission/40001/3","title":"European Journal of Medical Research","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Neonatal sepsis, time-to-antibiotic, antibiotic timing, in-hospital mortality, multicenter cohort study","lastPublishedDoi":"10.21203/rs.3.rs-9153479/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9153479/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eTimely initiation of antibiotic therapy is a cornerstone of sepsis management, yet evidence supporting strict time-based targets in neonatal sepsis remains limited and inconsistent. Whether incremental delays in time-to-antibiotic (TTA) administration are independently associated with adverse outcomes in neonates is uncertain.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe conducted a multicenter retrospective cohort study using a neonatal sepsis registry from five centers between January 2018 and December 2023. Hospitalized neonates with clinically diagnosed sepsis and documented TTA were included. TTA was analyzed as both a continuous variable and categorized into \u0026lt;\u0026thinsp;1 h, 1\u0026ndash;2 h, 2\u0026ndash;3 h, 3\u0026ndash;6 h, and \u0026gt;\u0026thinsp;6 h, with an additional binary comparison of early (\u0026lt;\u0026thinsp;1 h) versus delayed (\u0026ge;\u0026thinsp;1 h) administration. The primary outcome was in-hospital mortality. Secondary outcomes included hospital length of stay, duration of mechanical ventilation, secondary infection, and a composite adverse outcome. Multivariable logistic regression and Cox proportional hazards models were used to estimate adjusted associations, controlling for prespecified clinical covariates.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eAmong 1,500 neonates with sepsis, median TTA was 0.76 hours, and 58.0% received antibiotics within 1 hour. Overall in-hospital mortality was 15.9%. Mortality increased modestly across TTA categories, from 15.3% (\u0026lt;\u0026thinsp;1 h) to 20.0% (\u0026gt;\u0026thinsp;6 h) (trend P\u0026thinsp;\u0026asymp;\u0026thinsp;0.024). In adjusted analyses, each 1-hour delay in antibiotic administration was associated with a higher, but not statistically significant, odds of mortality (adjusted OR 1.090; 95% CI 0.975\u0026ndash;1.217). Kaplan\u0026ndash;Meier analyses demonstrated significant survival differences across detailed TTA strata, whereas the binary comparison of \u0026lt;\u0026thinsp;1 h versus \u0026ge;\u0026thinsp;1 h was not significant. Longer TTA was associated with a small increase in hospital length of stay, while other secondary outcomes showed no clear linear association. Subgroup and sensitivity analyses yielded directionally consistent results.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e \u003cp\u003eIn this multicenter cohort of neonates with sepsis, longer delays in antibiotic administration were associated with modestly worse outcomes, with excess risk concentrated among more prolonged delays rather than marginal deviations beyond 1 hour. These findings support efforts to minimize extreme treatment delays while suggesting that rigid application of a universal 1-hour threshold may not fully capture risk heterogeneity in neonatal sepsis.\u003c/p\u003e","manuscriptTitle":"Data analysis from the Sepsis Registry study on the association between antibiotic use duration and clinical outcomes in neonatal sepsis","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-27 14:12:53","doi":"10.21203/rs.3.rs-9153479/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-05-08T16:33:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"43480329439687492256317175445075120628","date":"2026-04-20T09:18:16+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"19414018199228010102839100490318834724","date":"2026-04-19T15:46:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"160702218910617454521256295357395858612","date":"2026-04-18T18:11:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-17T15:17:39+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-19T09:25:58+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-19T09:25:44+00:00","index":"","fulltext":""},{"type":"submitted","content":"European Journal of Medical Research","date":"2026-03-18T01:51:50+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"european-journal-of-medical-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ejmr","sideBox":"Learn more about [European Journal of Medical Research](http://eurjmedres.biomedcentral.com)","snPcode":"40001","submissionUrl":"https://submission.nature.com/new-submission/40001/3","title":"European Journal of Medical Research","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"96f8abbe-59b7-4c38-896f-ffd60983158a","owner":[],"postedDate":"April 27th, 2026","published":true,"recentEditorialEvents":[{"type":"editorInvitedReview","content":"","date":"2026-05-08T16:33:05+00:00","index":26,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-27T14:12:54+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-27 14:12:53","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9153479","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9153479","identity":"rs-9153479","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}