Comparison of broth enhancement to direct plating for screening of rectal cultures for ciprofloxacin-resistant Escherichia coli

Michael A. Liss, Kristen K. Nakamura, Ellena M. Peterson

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

A transrectal prostate biopsy is the most common procedure used to establish the diagnosis of prostate cancer. Prior to biopsy, patients are commonly given ciprofloxacin for prophylaxis. However, a complication of the procedure is infection with ciprofloxacin-resistant organisms, in particular resistant Escherichia coli. In order to identify patients carrying ciprofloxacin-resistant E. coli, so as to tailor their antibiotic prophylaxis, rectal swabs are screened using selective broth and/or solid medium. In our evaluation, we compared broth enrichment and direct plating techniques by using brain heart infusion broth and MacConkey agar containing 1 μg/ml or 10 μg/ml of ciprofloxacin. Of the 100 patients included in the study, 20 were colonized with ciprofloxacin-resistant organisms, 19 of which were E. coli. There was no significant difference (P > 0.1) between the culture methods or the ciprofloxacin concentrations in the medium when identifying patients with ciprofloxacin-resistant E. coli; however, broth enrichment using 1 μg/ml ciprofloxacin was the most sensitive at 100%, but it was the least specific. Direct plating of rectal swabs onto MacConkey agar containing 10 μg/ml of ciprofloxacin was 100% specific and missed only 1 positive specimen, with a sensitivity of 94.7%; this method was the most cost-effective. Therefore, direct plating of rectal swabs onto selective medium proved to be a sensitive and cost-effective approach in identifying patients colonized with ciprofloxacin-resistant E. coli.

Original languageEnglish (US)
Pages (from-to)249-252
Number of pages4
JournalJournal of clinical microbiology
Volume51
Issue number1
DOIs
StatePublished - Jan 2013

ASJC Scopus subject areas

  • Microbiology (medical)

Fingerprint Dive into the research topics of 'Comparison of broth enhancement to direct plating for screening of rectal cultures for ciprofloxacin-resistant Escherichia coli'. Together they form a unique fingerprint.

Cite this