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.

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.

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.

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.