Surgical site infections (SSI) pose a considerable risk in gynecologic cancer surgery due to their potential for complications such as wound dehiscence, abscess formation, and prolonged hospitalization. These infections not only impact patient morbidity and mortality but also contribute to increased healthcare costs. To mitigate this risk, pre-operative antibiotic prophylaxis is routinely administered. Cefazolin is commonly used for this purpose in clean-contaminated surgeries like hysterectomy.

However, recent evidence suggests that adding metronidazole to cefazolin may further reduce the incidence of SSIs by targeting anaerobic bacteria, which are prevalent in the pelvic region. This study was published in the American Journal Of Obstetrics and Gynecology. The study was conducted by Anne K. and colleagues.
Gynecologic cancer surgeries, including hysterectomy and oophorectomy, are associated with an increased risk of SSIs due to factors such as the proximity to the perineum, the potential for contamination from the genital tract, and the complexity of the procedures. SSIs can lead to adverse outcomes such as delayed wound healing, prolonged hospital stays, and the need for additional interventions.
This retrospective cohort study was conducted at a comprehensive cancer center and included patients undergoing gynecologic surgery between May 2017 and June 2023. The study compared two groups of patients: those who received cefazolin alone as antibiotic prophylaxis (pre-intervention group) and those who received a combination of cefazolin and metronidazole (post-intervention group). The primary outcome assessed was the incidence of SSI within 30 days post-surgery. Multivariable logistic regression analysis was performed to identify factors independently associated with SSI while adjusting for potential confounding variables.

The key findings of the study were:
• Among the 3343 patients included in the study, the majority (76.9%) belonged to the pre-intervention group, while the remaining 23.1% were in the post-intervention group.
• The overall SSI rate prior to the intervention was 4.7%, compared to 2.6% after the intervention, indicating a significant reduction in SSIs following the addition of metronidazole to cefazolin.
• The addition of metronidazole to cefazolin resulted in a notable decrease in the odds of developing an SSI.
• Patients receiving the combination regimen had a 49% lower odds of experiencing an SSI compared to those receiving cefazolin alone.
• This reduction in SSI risk remained significant even after adjusting for potential confounders.
The findings of this study underscore the significant impact of adding metronidazole to cefazolin in reducing the incidence of SSIs in gynecologic cancer surgery. Providers should consider implementing this combination regimen as part of their antibiotic prophylaxis protocols, especially for patients undergoing procedures such as hysterectomy. By optimizing antibiotic prophylaxis, healthcare providers can improve patient outcomes and enhance the quality of care in gynecologic oncology.
Reference:
Knisely, A., Iniesta, M. D., Marten, C. A., Chisholm, G., Schmeler, K. M., & Taylor, J. S. (2024). Metronidazole and cefazolin versus cefazolin alone for surgical site infection prophylaxis in gynecologic surgery at a comprehensive cancer center. American Journal of Obstetrics and Gynecology. https://doi.org/10.1016/j.ajog.2024.03.043