Antibiotic susceptibility of intestinal Escherichia coli in men undergoing transrectal prostate biopsies: a prospective, registered, multicentre study.

OBJECTIVES: To determine, in a prospective, multicentre setting, the prevalence of fluoroquinolone-resistant (FQ-R) and extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E. coli) strains in men undergoing transrectal ultrasonography-guided prostate biopsy (TRUS-Bx) in Finland; and to survey the associated risk factors for having the previously mentioned strains.

PATIENTS AND METHODS: This is a substudy of the trial investigating the role of magnetic resonance imaging (MRI) in prostate cancer diagnosis (Improved Prostate Cancer Diagnosis - Combination of Magnetic Resonance Imaging Targeted Biopsies and Biomarkers Multi-institutional Study [multi-IMPROD], NCT02241122). In all, 359 patients from four study centres were recruited to this prospective study. After having signed the informed consent form, these men with suspicion of prostate cancer completed a detailed questionnaire on their medical, smoking, and travelling history, as well as their recent use of antibiotics. After the bi-parametric MRI scan, TRUS-Bx was taken and a rectal swab sample was collected and cultured for determining the antimicrobial susceptibility profile of E. coli strains. The potential risk factors for having FQ-R or third-generation cephalosporin-resistant (3GC-R) E. coli strains were analysed using univariate and multivariate logistic regression analysis.

RESULTS: The percentage of FQ-R and 3GC-R E. coli strains amongst the study population was 13% and 8%, respectively. Amongst patients having E. coli strains, the rate of FQ-R and 3GC-R strains was 14% and 8%, respectively. Of the 3GC-R E. coli strains, 62% proved to be ESBL-producers and 88% were also FQ-R. In multivariate analysis, international travel during the preceding year significantly increased the risk of having a FQ-R E. coli strain (odds ratio [OR] 3.592, P = 0.001) and, unexpectedly, use of antibiotics during the previous year significantly decreased this risk (OR 0.442, P = 0.035). No significant risk factors for having 3GC-R E. coli were identified.

CONCLUSION: The occurrence of intestinal FQ-R and/or 3GC-R (potentially ESBL-producing) E. coli strains in men undergoing TRUS-Bx in Finland is notable. The finding is consistent with the global increase in antimicrobial resistance. International travel appears to be an indisputable risk factor for having intestinal FQ-R E. coli strains. The contemporary antimicrobial resistance situation should be taken into account in the care of post-TRUS-Bx infections.