Modification of an evidence-based protocol for advanced appendicitis in children.

INTRODUCTION: We previously developed an evidence-based clinical pathway for children with advanced appendicitis. The pathway standardized the choice and duration of antibiotic therapy and established discharge criteria. Initially, the pathway led to a 50% decrease in the rate of superficial and deep surgical site infections and a significant decrease in hospital length of stay. Four years after implementation, we noted an increase in the infectious complication rate and the emergence of resistant bacteria to commonly used antibiotics. In this study, we prospectively collected peritoneal fluid cultures at the time of appendectomy in an effort to optimize our antibiotic therapy and decrease complication rates.

METHODS: Microbiology analysis of peritoneal fluid cultures obtained at the time of appendectomy was performed in patients with an intraoperative diagnosis of advanced appendicitis. Clinical information, including demographics, laboratory data, and postoperative outcomes were collected and compared to the historic cohort. X(2), Student's t-test, and Fisher exact test were used where appropriate.

RESULTS: The historic and prospective cohorts were similar with respect to clinical and demographic data. The postoperative intra-abdominal abscess rate remained unchanged (28% from 24%, P = 0.603). Escherichia coli and Pseudomonas aeruginosa were the most commonly isolated aerobic bacteria from peritoneal fluid in the prospective cohort. Thirty-two percent of these patients had Pseudomonas spp., and 12% had Enterococcus spp. or Escherichia coli resistant to cefoxitin in their peritoneal fluid cultures.

DISCUSSION: A significant proportion (40%) of children with advanced appendicitis had organisms either not susceptible or resistant to our first line antibiotic in their peritoneal fluid cultures. Our clinical pathway now recommends piperacillin-tazobactam as the most effective empiric therapy for advanced appendicitis in children. Microbiologic analysis of peritoneal fluid at appendectomy may be used to tailor antibiotic therapy in advanced appendicitis.