Ciprofloxacin resistance in the faecal carriage of patients undergoing transrectal ultrasound guided prostate biopsy.

UNLABELLED: WHAT'S KNOWN ON THE SUBJECT? AND WHAT DOES THE STUDY ADD?: Transrectal ultrasound guided prostate biopsies (TRUSBx) are associated with a spectrum of complications, including most significantly infection, which affects up to 5% of patients. In the most severe cases, infection leads to sepsis, a life-threatening complication. Escherichia coli is the primary responsible pathogen. Although antibiotic prophylaxis with fluoroquinolones is routinely used, there is evidence that the infection rate after TRUSBx is increasing, and this appears to be due to an increasing prevalence of ciprofloxacin-resistant rectal flora. This is the largest prospective clinical trial to date analysing the rectal flora of men undergoing prostate biopsies. We determined the microbial and antibiotic sensitivity profiles from 849 patients. Ciprofloxacin-resistant Gram-negative organisms were identified in the rectal flora of 19.0% of men. Furthermore, fluoroquinolone use within 6 months preceding a TRUSBx and the presence of a prosthetic heart valve were significant predictors of ciprofloxacin resistance on rectal swab. Determining the prevalence of rectal fluoroquinolone resistance has important implications in evaluation of the suitability of prophylactic regimens. Antimicrobial profiles derived from rectal swabs pre-biopsy may prove useful in guiding targeted antibiotic prophylaxis.

OBJECTIVES: To establish the prevalence of ciprofloxacin-resistant bacteria in patients undergoing transrectal ultrasound guided prostate biopsies (TRUSBx) and to determine whether this predicts subsequent infectious complications. To identify risk factors for harbouring ciprofloxacin-resistant flora.

PATIENTS AND METHODS: Any patient undergoing a TRUSBx from 2009 to 2011 was eligible for enrolment in this prospective study. Pre-biopsy rectal and urine cultures and post-biopsy urine cultures were obtained and antimicrobial susceptibility was determined. Univariate and multivariate analyses were performed to identify independent patient risk factors associated with ciprofloxacin-resistant rectal flora.

RESULTS: A total of 865 patients underwent TRUSBx, of whom 19.0% were found to have ciprofloxacin-resistant Gram-negative coliforms. Escherichia coli was the most prevalent Gram-negative rectal isolate (80.9%) and accounted for 90.6% of ciprofloxacin resistance. Patient characteristics that conferred an increased risk of harbouring ciprofloxacin-resistant organisms included a history of a heart valve replacement (P < 0.05) and ciprofloxacin use in the past 3 months (P < 0.05). Infectious complications were observed in 3.6% (n = 31) of the patient population and 48% of these patients grew ciprofloxacin-resistant organisms on the pre-biopsy rectal swab (P < 0.001).

CONCLUSIONS: Antimicrobial resistance to ciprofloxacin in the rectal flora was common, particularly in patients with recent ciprofloxacin use and a heart valve replacement. Despite a significant correlation between those patients who developed infections and the detection of ciprofloxacin-resistant organisms, only 9.0% (n = 15) of the total group with ciprofloxacin resistance developed an infectious complication. Future studies will need to evaluate the cost effectiveness and clinical utility of a pre-biopsy rectal culture in targeting antibiotic prophylaxis.