Extended antimicrobial prophylaxis showed no infection reduction after colorectal resection

A retrospective propensity score-matched study of 2,691 patients undergoing colorectal resection found that extending prophylactic antimicrobial use beyond 48 hours postoperatively was not statistically associated with fewer surgical site infections or other healthcare-associated infections. The analysis also found no statistically significant difference in postoperative hospital stay between the groups, while total costs were higher among patients receiving extended prophylaxis. The findings apply to the retrospective cohort studied and do not establish that prolonged prophylaxis is ineffective in every clinical setting.

The researchers reviewed patients who underwent colorectal resection between March 1, 2023, and December 31, 2025. They classified 1,934 patients as receiving no prophylactic antimicrobial use beyond 48 hours after surgery and 757 as receiving prophylaxis beyond that period. In the full cohort, 229 patients, or 8.51%, developed a surgical site infection, while 217, or 8.06%, developed another healthcare-associated infection. These figures describe the observed incidence of the two outcomes across the entire study population before matching.

To address differences in measured characteristics between the two groups, the investigators used propensity score matching. After matching, each group contained 757 patients. Multiple regression was then used to evaluate the association between extended prophylaxis and infection while adjusting for age, sex, diabetes, hypertension, anemia and hypoproteinemia. In these analyses, prophylactic antimicrobial use beyond 48 hours was not significantly associated with surgical site infection, for which the adjusted odds ratio was 0.85, the 95% confidence interval was 0.59–1.21 and the P value was 0.356. For other healthcare-associated infections, the adjusted odds ratio was 0.81, the 95% confidence interval was 0.54–1.23 and the P value was 0.325.

The estimates were similar after the researchers performed an additional adjustment for all confounding factors included in the analysis. The odds ratio for surgical site infection was 0.85, with a 95% confidence interval of 0.59–1.22 and a P value of 0.372. For other healthcare-associated infections, the odds ratio was 0.77, with a 95% confidence interval of 0.50–1.18 and a P value of 0.229. Thus, neither model detected a statistically significant association between extended antimicrobial prophylaxis and a reduction in the measured infections. The confidence intervals included an odds ratio of 1, indicating that the data did not rule out associations in either direction with the precision available in the study.

Postoperative hospital stay did not differ significantly between the groups, with a P value above 0.05, but total costs were higher in the group receiving prophylaxis beyond 48 hours. Reported total costs were ¥57,349.60 for the extended-prophylaxis group and ¥55,039.10 for the group without prophylaxis beyond 48 hours, a difference with a P value of 0.0006. Because the study was retrospective and observational, the results show associations rather than establishing that extended antimicrobial use caused higher costs or that it failed to prevent infections. The authors said the analysis may contribute to strategies for standardizing prophylactic medication management during the perioperative period of colorectal resection.

Subject of Research: Postoperative antimicrobial prophylaxis and infection risk after colorectal resection

Article Title: Extending prophylactic antimicrobial use beyond 48 h postoperatively fails to reduce surgical site infections and other healthcare-associated infections in patients undergoing colorectal resection: a Propensity Score Matching study

Article References: Yang, Y., Bao, Z., & Zhang, Z. (2026). Extending prophylactic antimicrobial use beyond 48 h postoperatively fails to reduce surgical site infections and other healthcare-associated infections in patients undergoing colorectal resection: a Propensity Score Matching study. BMC Infectious Diseases, 26(1), Article 1815. https://doi.org/10.1186/s12879-026-14143-3

Image Credits: AI Generated

DOI: 10.1186/s12879-026-14143-3

Keywords: colorectal resection, antimicrobial prophylaxis, surgical site infection, healthcare-associated infection, propensity score matching, retrospective cohort, hospital stay, healthcare costs, Extending, prophylactic, antimicrobial, beyond