Antibiotics and Surgically Treated Acute Appendicitis, When, Where, and Why?

Background: Antibiotics within an hour of incision reduce the incidence of surgical site infection (SSI) in clean-contaminated abdominal surgery. However, patients undergoing emergency surgery for an intra-abdominal infectious process often receive treatment antibiotics and may not benefit from additional pre-incisional antibiotics (POA). We hypothesized that POA would not lead to a reduction in the occurrence of SSIs following emergency appendectomy. Patients and Methods: All patients at a single institution undergoing emergency appendectomies for acute appendicitis from 2013 to 2020 were included. Age, gender, perforation, body mass index (BMI), Elixhauser comorbidity index (ECI), surgical approach, emergency department antibiotics (EDA), EDA administration time, and pre-operative antibiotics were abstracted. Primary outcomes were superficial/deep and organ-space SSIs. Bi-variable logistic regression models assessed the independent impact of each tactic. Multi-variable models compared those receiving pre-incisional cefazolin with those receiving no POA. Results: Patients (n = 1380) had a mean age (standard deviation) of 39.5 (17.0) years, and 48.6% were female. Age, gender, perforated appendicitis, EDA, ECI, and BMI all were predictive of infection. POA were not predictive of SSI (p = 0.632). After adjustment for age, gender, perforation, EDA, EDA administration timing, ECI, and BMI, only perforation (odds ratio [OR]: 17.08, 95% confidence interval [CI] = 6.97-51.43) and male gender (OR: 2.75, 95% CI = 1.29-6.43) were associated with organ-space infection, whereas pre-incisional cefazolin was not (OR: 0.83, 95% CI = 0.38-1.97). Emergency department broad-spectrum antibiotics were associated with a lower incidence of superficial/deep infection (OR: 0.06, 95% CI = 0.00-0.68); however, pre-incisional cefazolin was not (OR: 0.71, 95% CI = 0.08-15.34). Conclusion: For patients undergoing emergency appendectomies who have received broad-spectrum antibiotic treatment, additional pre-incisional cefazolin does not reduce the incidence of superficial/deep or organ-space SSI.