Cefoxitin for Intraamniotic Infections and Endometritis: A Retrospective Comparison to Traditional Antimicrobial Therapy Regimens within a Health System.

BACKGROUND:Local institutional guidelines and order sets were updated in June 2023 to recommend first-line cefoxitin monotherapy for the treatment of intraamniotic infections (IAI) and endometritis. This study evaluated the clinical impact of this change. METHODS:This was a retrospective, observational cohort study in an 11-campus health system comparing clinical outcomes of patients with chorioamnionitis, endometritis, or septic abortion receiving intravenous antimicrobial therapy before and after implementation of first line cefoxitin monotherapy recommendations for the treatment of these infections. Primary outcome was a composite of serious clinical events post-delivery, i.e., ICU admission, death, hospital readmission related to IAI or endometritis within 30 days, additional surgery or procedures, or deep surgical site infection. Baseline characteristics between the pre- and post-cefoxitin groups were compared via Student's t tests for continuous variables and Chi square tests for categorical variables. Outcomes were evaluated via generalized linear modeling. RESULTS:A total of 472 patients were enrolled, 350 (74%) in the pre-cefoxitin group and 122 (26%) in the post-cefoxitin group. Groups were significantly different by race, healthcare payor, and hospital campus. Cefoxitin was rarely used in the pre-cefoxitin group (n = 2,  < 0.1%) and commonly used in the post-cefoxitin group (n = 112, 91.8%). After controlling for group differences, odds of experiencing serious clinical event post-delivery in the post-cefoxitin group were non-inferior to those in the pre-cefoxitin group (adjusted odds ratio 0.37 [95% CI: 0.17-0.76], p = 0.010). CONCLUSION:Local institutional guidelines with predominant use of cefoxitin therapy were non-inferior to traditional antimicrobial therapy regimens for the treatment of IAI.