Rate of bacterial positivity following antibiotic initiation: A systematic review and meta-analysis

Background Bacterial culture remains a critical tool for pathogen identification and antimicrobial susceptibility testing. However, its diagnostic accuracy is often compromised by prior antibiotic administration, which can reduce the recovery of viable organisms and lead to false-negative results. Given the variability and limitation in existing studies, a systematic review is needed to better understand the influence of antibiotics on culture yield. Methods We conducted an electronic search in PubMed, Embase, Scopus and Web of Science from their inception through March 2025. The Newcastle-Ottawa Scale was used to assess the methodological quality of the included articles. Random effect models were used to estimate the proportions and 95% Confidence Intervals (CI). The protocol for this review was registered in the PROSPERO: CRD42025648397. Results Of the 1,226 articles obtained from the search, 11 were eligible. They consisted of 67,330 samples with culture results after antibiotic administration. The pooled proportion for bacterial growth was 37% (95% CI: 20%-56%) and 18% (95% CI: 10%-29%) before and after antibiotic administration, respectively. Significant heterogeneity ( I ² : 99.8%, p-value = 0) was observed across the included studies. Conclusion Bacterial growth decreased by more than half following antibiotic administration, indicating a strong suppressive effect. This highlights the importance of considering the timing of sample collection in relation to antibiotic initiation. Where necessary, particularly in cases of uncertain clinical progress, sampling after antibiotic administration can be useful for monitoring prognosis and guiding further treatment decisions.