Clinical and Microbiological Determinants of Infection After Transrectal Prostate Biopsy

Abstract

The rectal colonizing E. coli population is the source for most fluoroquinolone-resistant post-TPB infections, regardless of clonal background or virulence traits. Screening cultures can identify nearly all patients at risk for fluoroquinolone-resistant post-TPB infection.

Rapid Identification of Rectal Multidrug-resistant Escherichia coli Before Transrectal Prostate Biopsy

“…Rectal swabs were streaked onto locally prepared ciprofloxacin-supplemented (4 mg/L) MacConkey agar plates, which were quality-controlled using fluoroquinolone-susceptible and resistant E. coli isolates (20). A representative culture of each distinct colonial morphotype was selected for identification and susceptibility using the Vitek 2 instrument (BioMerieux, Durham, NC) GN identification cards based on the Clinical and Laboratory Standards Institute interpretative criteria.…”

“…(3, 7, 14, 16–19) Detecting FQ resistant E. coli in feces prior to biopsy would identify men who at higher risk of infection from introduction of ExPEC into the prostate and bloodstream during the biopsy (20). These men would be candidates for alternative or additional antibiotic prophylaxis.…”

Cutting to the Core of the Issue: Emerging Strategies To Reduce Prostate Biopsy-Related Infections

“…A series of recent studies reviewed by Williamson et al reported that the majority of E. coli isolates recovered from infections were fluoroquinolone resistant, and furthermore, that a number exhibited additional antimicrobial resistance, primarily third-generation cephalosporin resistance or the identification of extended-spectrum ␤-lactamases (ESBL) or gentamicin resistance (13). Liss et al reported that patients' fluoroquinolone-resistant colonizing bacteria are the sources of most infections, demonstrating that pulsed-field gel electrophoresis profiles were indistinguishable for nine patients with paired isolates available from prebiopsy rectal screening and postbiopsy infection (14).…”

“…However, susceptibility data from more than 16,000 worldwide E. coli isolates available in the European Committee on Antimicrobial Susceptibility Testing (EUCAST) MIC distribution website demonstrate that less than 3% of resistant E. coli had MIC values between 4 and 8 g/ml, with the greatest number of resistant isolates having an MIC of 32 g/ml (31). A study evaluating organisms from men undergoing prostate biopsy demonstrated that all ciprofloxacin-resistant E. coli had MIC values of Ͼ32 g/ml, suggesting that media containing 10 g/ml of ciprofloxacin should effectively detect the majority of resistant E. coli (14). A comparison of screening culture methods evaluating direct plating and broth enrichment with 1 and 10 g/ml of ciprofloxacin-containing media found no significant differences in the detection of ciprofloxacin-resistant E. coli between any of the methods tested (32).…”

Editorial Comment

“…Patients with fluoroquinolone-resistant Escherichia coli are significantly more likely to develop postbiopsy infections than noncolonized individuals, 2 and several small studies have reported no infectious complications after switching to a targeted approach based on rectal swab cultures. 3,4 An alternative way to reduce infection is to change the biopsy technique.…”