Fluoroquinolone-resistant Escherichia coli carriage in transrectal prostate biopsy patients without infectious complications

Fluoroquinolones are a commonly used prophylaxis in transrectal ultrasound-guided prostate biopsy (TRUS-Bx), even though fluoroquinolone-resistant Escherichia coli has been associated with infectious complications after TRUS-Bx. The present study describes fluoroquinolone resistance mechanisms and antimicrobial susceptibility among intestinal E. coli, isolated from TRUS-Bx patients in a prospective study showing very few infectious prostate biopsy adverse events. This Multi-IMPROD sub-study included a total of 336 patients who received either ciprofloxacin, levofloxacin, or fosfomycin as prophylaxis before TRUS-Bx. E. coli could be cultured from 278 fecal swab samples, and 27 (9.7%) of these showed resistance to ciprofloxacin, and 14 (5.0%) were susceptible with increased exposure (I). Chromosomal and transferable fluoroquinolone resistance mechanisms were found among ciprofloxacin non-susceptible isolates, but both qnr genes and single gyrA mutations were found also among the ciprofloxacin-susceptible E. coli population. Low-level fluoroquinolone resistance is commonly associated with ESBL production in Enterobacterales. However, ESBL and qnr genes were not associated in our material, 14 isolates were ESBL producers and only 14.3% of them had the qnr gene, although 85.7% of the ESBL producers were ciprofloxacin non-susceptible. In the Multi-IMPROD substudy, only two mild urinary tract infections were reported, indicating that the antimicrobial susceptibility or resistance pattern of E. coli does not correlate with the onset of post-biopsy adverse events. We conclude that in our clinical settings, ciprofloxacin and levofloxacin prophylaxis is effective, and no severe post-biopsy infections were detected despite the intestinal colonization of genotypically and phenotypically fluoroquinolone-resistant E. coli.