Management and Microbiology of Perforated Appendicitis in Pediatric Patients: A 5-Year Retrospective Study.

Introduction: This study aims to assess the current epidemiology and microbiology of perforated appendicitis, how antibiotic choice and duration correlate with meaningful clinical outcomes, and whether serial white blood cell (WBC) counts provide clinical value.

Methods: Five-year retrospective cohort study, 2015-2019, among 333 consecutive children, ages 0-18 years, treated at St. Louis Children's Hospital for perforated appendicitis. Main outcomes included length of stay (LOS), postoperative abscess formation, and readmission. Statistical analysis was performed with uni- and multi-variate analyses.

Results: Intra-abdominal cultures most commonly grew Bacteroides fragilis (52%) and Escherichia coli (50%). Patients who initially received broad-spectrum antibiotics (meropenem, piperacillin-tazobactam, fourth-generation cephalosporins) for perforated appendicitis had greater rates of postoperative abscess formation (25% vs. 12%, p < 0.01) and LOS (7.0 vs. 5.7 days, p < 0.01). Similarly, antibiotics at time of discharge were associated with greater postoperative abscess formation (22% vs. 9%, p < 0.01) and LOS (6.4 vs. 5.6 days, p = 0.02). However, discharge with strictly oral antibiotics was not correlated with greater LOS, postoperative abscess formation, or readmission rates compared to discharge without antibiotics. Serial WBC counts had no predictive value for LOS, postoperative abscess formation, or readmission.

Conclusions: Bacteroides fragilis and E. coli were the most common intra-abdominal microbes for perforated appendicitis among our cohort. In non-critically ill children, the routine use of broad-spectrum antibiotics or continuation of antibiotics beyond discharge was not correlated with improved clinical outcomes. Additionally, WBC counts were not correlated with meaningful clinical outcomes.