Abstract / Summary
Abstract Purpose Appendicitis, characterized by inflammation of the vermiform appendix, remains the leading cause of acute abdomen worldwide. Emerging evidence suggests that alterations in the intestinal microbiota may play a role in its pathogenesis. This study aimed to analyze the prevalence and microbiological profile of bacteria identified in pediatric patients with complicated acute appendicitis. Methods A systematic review was conducted, including studies published up to April 2026 within a 12-year timeframe. Twenty-three observational cohort studies met the inclusion criteria and were included in the qualitative synthesis. Among these, studies reporting patient-level prevalence and using culture-based methods were included in the quantitative analysis. Results The findings demonstrated that Escherichia coli was the most frequently identified microorganism in pediatric complicated appendicitis. Other commonly detected bacteria included Streptococcus spp., Bacteroides spp., Pseudomonas spp., Enterococcus spp., and Klebsiella spp. However, the certainty of the evidence for these findings remains low. Substantial methodological heterogeneity was observed across studies, particularly regarding sample collection, microbiological techniques, and outcome reporting, which limits the comparability and generalizability of the results. Conclusion In conclusion, while Escherichia coli appears to predominate in pediatric complicated acute appendicitis, the available evidence is limited and should be interpreted with caution. Future well-designed multicenter studies using standardized protocols are essential to improve the consistency of findings and strengthen the overall evidence base.