K.T. Wirth1,2, T. Steele1,4, M. Byrne1,3, D. Wakeman1, N.A. Wilson1,2 1University Of Rochester, Department Of Surgery, Division Of Pediatric Surgery, Rochester, NY, USA 2University Of Rochester, Department Of Biomedical Engineering, Rochester, NY, USA 3University Of Rochester, Department Of Surgery, Rochester, NY, USA 4McQuaid Jesuit High School, Rochester, NY, USA
Introduction: Complicated appendicitis is the most common cause of intraabdominal contamination in children, with ~25-30% of pediatric appendicitis presenting with complicated appendicitis. These patients account for most of the morbidity associated with appendicitis. In 2019, our institution began collecting peritoneal aspirates for culture in all cases of complicated appendicitis. This study aimed to quantify the rate of pediatric complicated appendicitis at our institution and characterize the microbes that grew from peritoneal aspirates. We hypothesize that Escherichia coli will be the most cultured bacteria and that Pseudomonas aeruginosa will be present in a significant number of peritoneal cultures.
Methods: We performed a single-center retrospective cohort study after IRB approval. Patients were identified using our institutional NSQIP-Pediatric dataset (1/2016-12/2023), which includes all cases of pediatric appendicitis (age <18y). Additional data, including all culture, gram stain, and antibiotic sensitivity data, was abstracted from the electronic medical record. Descriptive statistics were performed to characterize this cohort. Frequency data are presented as %(n).
Results: Of the 1804 cases of pediatric acute appendicitis during the study period, 37% (667) were complicated appendicitis. Positive gram stains or cultures with growth were available for 35.8% (239) of patients with complicated appendicitis. 74.9% (174) had polymicrobial cultures. Escherichia coli was the most common organism identified at 64.3% (153), followed by Strep. anginosus at 43.3% (103), Bacteroides fragilis 36.6% (87), other Bacteroides species 20.2% (48), and Pseudomonas aeruginosa 19.8% (47) (Figure). A wide variety of other microbes were identified (e.g., other strep species, actinomyces), but each was found in fewer than 8% of specimens (range 0.42-7.98%).
Conclusion: This study characterizes the microbial epidemiology of pediatric complicated appendicitis over a 7-year period at a single institution. Consistent with previous studies, E. coli was the most cultured bacteria. Given the push toward decreasing hospital length of stay and in light of recently published guidelines from the Surgical Infection Society, which recommend only a short course (24-48 hr) of antibiotic therapy after appendectomy for complicated appendicitis, it is critical to know the institution-specific typical microbial spectrum. We are currently examining the antibiotic sensitivity profiles of the cultured bacteria.