Fluoroquinolone resistance colonization from initial to repeat prostate biopsy

Purpose: Fluoroquinolone (FQ) resistant (FQR) bacteria are a major cause of infection after transrectal prostate biopsy (TRPB). We determined the prevalence of FQR in initial and subsequent rectal cultures from men undergoing repeat prostate biopsies. Materials and methods: After IRB approval, men presenting for TRPB at the San Diego Veterans Affairs Medical Center between January 1, 2010, and February 6, 2014, underwent pre-TRPB rectal culture. The rectal swab was collected from the patient immediately prior to TRPB. Rectal swabs were streaked onto locally prepared ciprofloxacin-supplemented (4 mg/L) MacConkey agar plates. A representative colony was selected for identification and susceptibility testing. Results: Of 617 patients who had rectal cultures done, 7% (43/617) had a repeat rectal culture performed in relation to a second prostate biopsy. All cipro-resistant bacteria isolated were Escherichia coli. The median time and interquartile range between first and second biopsy was 2.3 years (range 1.2–3.6 years). On first biopsy, 16.3% (7/43) had FQR, which was not statistically different from the 18.6% of patients who had FQR on their second biopsy (p=0.78). Overall, 74% (32/43) of patients tested absent for FQR at both prostate biopsies, and 9.3% (4/43) tested present at both (p=0.015). However, 9.3% (4/43) converted from absent to present FQR, and 7.0% (3/43) converted from present FQR to absent (p=0.69). Seventy percent of the FQR E. coli were also resistant to gentamicin, and 22% were resistant to cefepime. Conclusions: Patients undergoing prostate biopsy should be examined for FQR prior to each individual biopsy because prior culture results do not always predict whether a patient will be colonized with FQR E. coli.