1521. Evaluation of the Microbiology of Intraabdominal Infections in Children and Implications for Treatment and Outcomes

BACKGROUND: Acute appendicitis is the most common surgical emergency in pediatric medicine. Pseudomonas aeruginosa has been reported in up to 23% of intraoperative cultures though current recommendations do not specify the need for antipseudomonal coverage for preoperative treatment. Prior to transitioning the empiric antibiotic regimen used in the management of perforated appendicitis from an antipseudomonal agent to a simplified daily antibiotic regimen, we conducted a retrospective review of bacterial cultures obtained from intraabdominal fluid collections and antibiotic regimens in children that underwent surgical treatment of perforated appendicitis and/or intraabdominal abscesses. METHODS: A retrospective chart review of electronic medical records was conducted for pediatric patients admitted with a diagnosis of perforated appendicitis and/or intraabdominal abscess between April 1, 2016 and April 30, 2018. RESULTS: Seventy-two patients met inclusion criteria for the study with abscess identified prior to surgery in 11 patients (42.3%). Intraabdominal cultures were obtained in 48 patients (66.7%). The predominant organisms isolated were Escherichia coli, Bacteroides fragilis, and alpha-hemolytic Streptococcus. P. aeruginosa was identified in 12 (24%) cultures and never as a single organism. The majority of patients received piperacillin/tazobactam empirically (91.7%) with a median duration of 5 days (IQR 2). Forty-four patients (61.1%) received oral antibiotics to continue therapy after discharge and 75% received amoxicillin/clavulanate. Of the 12 patients with P. aeruginosa isolated, all patients received piperacillin/tazobactam empirically and 8 (66.7%) were transitioned to oral antibiotics to complete therapy, of which only two regimens retained antipseudomonal coverage. CONCLUSION: Majority of intraabdominal cultures were polymicrobial and the isolation of P. aeruginosa did not appear to impact the choice of definitive antimicrobial therapy. The predominant organisms identified suggest that a non-antipseudomonal regimen (i.e., cephalosporin with metronidazole) may be considered for empiric antibiotic therapy for cases of perforated appendicitis. DISCLOSURES: All authors: No reported disclosures.