Characterization of ciprofloxacin resistant Escherichia coli isolates among men undergoing evaluation for transrectal ultrasound guided prostate biopsy

Chao Qi*, Michael Malczynski, Anthony J. Schaeffer, Grace Barajas, Robert B. Nadler, Marc H. Scheetz, Teresa R. Zembower

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Purpose: We determine the prevalence of ciprofloxacin resistant gram-negative bacilli in patients scheduled for transrectal ultrasound guided prostate biopsy, characterize the Escherichia coli strains recovered from this patient population, and characterize the mechanisms responsible for β-lactam and ciprofloxacin resistance. Materials and Methods: Rectal swabs from 991 patients were cultured for ciprofloxacin resistant gram-negative bacilli with a selective medium. Recovered E. coli isolates were further analyzed with susceptibility testing, pulsed field gel electrophoresis, plasmid isolation and sequencing. Results: A total of 193 ciprofloxacin resistant gram-negative bacilli were recovered and of these isolates 167 (87%) were E. coli. The prevalence of ciprofloxacin resistant E. coli in the study population was 17%. Only 38 (26%) of the 149 E. coli isolates that received susceptibility testing were susceptible to ampicillin and ampicillin-sulbactam. In select isolates transferrable plasmids carrying β-lactamase were responsible for the resistance to the β-lactam agents and other nonb-lactam antimicrobials. Diverse combinations of gyrA and parC mutations associated with fluoroquinolone resistance were identified. Strain typing and plasmid typing indicated that the E. coli isolates did not share a common origin. Conclusions: Of the patients in our study 17% carried ciprofloxacin resistant E. coli. Analysis of resistance mechanisms and plasmid analysis along with strain typing demonstrated that this patient population harbored organisms with heterogeneous phenotypic susceptibility, indicating that universal prophylaxis would not provide optimal coverage for patients undergoing transrectal ultrasound guided prostate biopsy.

Original languageEnglish (US)
Pages (from-to)2026-2032
Number of pages7
JournalJournal of Urology
Issue number6
StatePublished - Dec 2013


  • Biopsy
  • Drug resistance, microbial
  • Fluoroquinolones
  • Infection
  • Prostate

ASJC Scopus subject areas

  • Urology

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