Rectal Swab Culture–directed Antimicrobial Prophylaxis for Prostate Biopsy and Risk of Postprocedure Infection: A Cohort Study

Abstract

To examine the effect of rectal swab culture-directed prophylaxis on the incidence of prostate biopsy-associated infections. Secondary objectives were to determine the rate of fluoroquinolone resistance and extended-spectrum beta-lactamase production in local rectal flora. All men receiving prostate biopsies from February 2013 to February 2014 were included in a retrospective institutional review board-approved study. All received either a preprocedural rectal swab and culture-directed antimicrobial prophylaxis or routine fluoroquinolone antibiotics. Clinical information was collected on infectious complications treated within 30 days of biopsy. Chi-square test, Fisher exact test, and Welch t test were used for statistical analysis. Confounding variables were included in a multivariate logistic regression model. Of 487 total patients, 314 received preprocedure rectal cultures and 173 did not. Average ages were 62.7 and 64.1 years, respectively (P = .07). There was no difference in mean prostate-specific antigen value (P = .9), Charlson comorbidity score (P = .8), or ethnicity (P = .1). The rectal swab group was more likely to receive supplemental gentamicin (P < .001) and had fewer infectious complications (1.9% vs 2.9%; P = .5). On multivariate analysis, decreased odds of infection was associated with culture-directed antibiotics (odds ratio, 0.70; 95% confidence interval, 0.20-2.50; P = .6). However, the study was only powered to detect a 97% reduction in infections. The incidence of fluoroquinolone resistance and extended-spectrum beta-lactamase production was 12.1% and 0.64%, respectively. Our study was underpowered but suggests that there are lower odds of infection with rectal swab-directed antimicrobial prophylaxis. The local incidence of fluoroquinolone resistance is high. A prospective, randomized, controlled trial is warranted to further evaluate this intervention.