719 - Clinical Outcomes of Single versus Double Anaerobic Coverage for Intra-abdominal Infections

Background: Double anaerobic coverage (DAC) is often used for intra-abdominal infections (IAIs) post-operatively. The primary objective of the study was evaluating length of hospital stay (LOS), in-hospital post-operative complications, and re-admission within 30 days of discharge due to post-operative complications in patients who received piperacillin/tazobactam plus metronidazole versus piperacillin/tazobactam for IAIs post-operatively. The secondary objective was comparing in-hospital mortality and hospital-acquired Clostridioides difficile infections (CDI) between the two groups.

Methods: This was a retrospective, cohort study including adults with surgically managed IAIs at an urban community hospital between January 1, 2016 and June 30, 2019. The following data were collected: age, sex, body mass index, comorbidities, Charlson Comorbidity Index (CCI), 5-day post-operative body temperature, American Society of Anesthesiologists (ASA) pre-operative assessment score, surgical wound classification, and IAI diagnosis. Multivariate analysis and aggregate resampling of the sampling distribution were conducted. An alpha of < 0.05 was considered statistically significant.

Results: Out of 163 patients, 96 patients received piperacillin/tazobactam plus metronidazole and 67 patients received piperacillin/tazobactam. The patients who received DAC were sicker with higher CCI (p=0.021) and 5-day post-operative body temperature (p=0.013). They were also at a higher risk for surgical site infections (p=0.002). Double anaerobic coverage was more often used for acute cholecystitis (p=0.0001) and gastrointestinal perforations (< 0.0001). After adjusting for these variables, DAC was associated with longer LOS (median 9 days vs. 4 days, p< 0.0001) and in-hospital post-operative complications (23% vs. 9%, p< 0.0001). There were more re-admissions within 30 days of discharge due to post-operative complications in the single anaerobic coverage group (4% vs. 1%, p=< 0.0001). In-hospital mortality (4% vs. 0%) and hospital-acquired CDI (1% vs. 0%) were only observed in DAC group.

Conclusion: Double anaerobic coverage was associated with no clinical benefit in surgically managed IAIs and in some cases may produce worse outcomes.