Analyzing the Efficacy of Metronidazole as Additional Surgical Site Infection Prophylaxis in Patients Undergoing Hysterectomy [ID 2683482

Abstract

INTRODUCTION: The American College of Obstetricians and Gynecologists recommends cefazolin for antibiotic surgical prophylaxis for hysterectomy procedures. In 2018, hysterectomy surgical site infection (SSI) data at John Peter Smith Hospital demonstrated a higher proportion of anaerobic growth identified on cultures. The addition of metronidazole with cefazolin became surgical prophylaxis protocol at our institution. The purpose of the study is to compare rates of non-superficial SSI before and after the addition of metronidazole in hysterectomy procedures. METHODS: This was a retrospective cohort study of patients who underwent hysterectomy of any surgical approach from January 2015 to July 2023. The primary exposure of interest was administration of metronidazole with additional covariates including age, body mass index, diabetes, oncology status, and wound class. The association between metronidazole administration and non-superficial SSI was examined using a logistic regression model. Appropriate waiver was received from the institutional IRB. RESULTS: Two thousand five hundred thirty-four hysterectomies were included in our cohort. 1,207 (44%) cases had metronidazole administration, with 98% of those cases occurring after the antibiotic was incorporated into the protocol. Of the patients who did not receive metronidazole, 49 (3.7%) patients had a non-superficial SSI compared to 14 (1.2%) patients that had a non-superficial SSI with metronidazole administration. After adjusting for age and oncology status, patients who did not receive metronidazole had higher odds of having a SSI compared those who did (adjusted odds ratio [aOR]: 3.6; 95% CI: 1.97, 6.3; P≤.0001). CONCLUSION: The results demonstrate potential infection prevention benefit with metronidazole to patients undergoing hysterectomy, supporting the institutional prophylaxis protocol. The findings could have further implications across hospitals with similar patient populations.