P1.072: The Impact of Cultures on Treating Abscesses Associated with Appendicitis

Background: Perforated appendicitis is associated with elevated risk of post-operative intra-abdominal abscess (PIAA) formation. Small PIAAs can be successfully treated without drainage, while larger ones warrant drainage. Routine culture of drained abscesses occurs at most institutions, with some prior studies showing antimicrobial resistance rates of 40-50%, prompting change of post-drainage antibiotics. The purpose of our study is to evaluate if culture results impact the antimicrobial therapy chosen for patients with PIAA, with our hypothesis being that routine culture does not have a significant impact on patient outcomes.

Methods: Patients < 18 years of age who were treated for perforated appendicitis at a standalone tertiary children’s hospital from 2011 to 2024 were retrospectively evaluated for abscess formation. We extracted those who underwent drainage procedures with abscess cultures to assess the need for antibiotic adjustments from the standard of care based on culture results.

Results: A total of 1736 patients treated for perforated appendicitis were identified, of which 181 developed a PIAA (10.4%). 80 patients were managed with standard of care antibiotics alone, while 111 underwent drainage with culture. 14 patients (12.6%) had a change in antibiotics based on resistant culture results. Six (6) changes were due to Pseudomonas, 4 due to Candida species, 2 due to Enterococcus, and 1 from resistant E. Coli and Eggerthella each. Those who underwent antibiotic changes had a prolonged total treatment course, with median therapy days of 27.7 versus 23.5 in those without change (p-value 0.02).

Conclusion: We found a lower than previously reported rate of antimicrobial resistance to standard therapy. Smaller abscesses resolved with antibiotic treatment alone, without drainage or identification of specific cultures. Most abscesses resolved with just standard therapy and changes to antibiotic therapy were strictly driven by cultures and not necessarily clinical deterioration. Given these findings, routine cultures may not be necessary in the treatment of PIAA.