2130 BACTERIAL GROWTH IN THE RECTUM AND URINE BEFORE AND AFTER TRANS-RECTAL ULTRASOUND-GUIDED PROSTATE BIOPSY

Abstract

INTRODUCTION AND OBJECTIVES: It is common practice to administer infection prophylaxis with a fluoroquinolone prior to performing transrectal ultrasound-guided prostate biopsy (TRUSBx). Infectious complications, however, continue to pose a significant risk to patients undergoing TRUSBx. In this prospective study we aimed to characterize bacterial growth in cultures obtained from the rectum and urine of patients undergoing TRUSBx, with a focus on ciprofloxacin-resistant organisms (CRO). METHODS: In this ethics board-approved, prospective, randomized trial investigating the efficacy of rectal antisepsis at the time of TRUSBx, a urine sample was taken for culture before and 48 hours after TRUSBx. A swab for culture was also obtained from the rectal mucosa overlying the prostate immediately prior to biopsy. Every patient received 3 days of ciprofloxacin starting the day before the biopsy. The first urine but not the rectal culture preceded the prophylaxis. Half of the patients received rectal cleansing with Povidoneiodine after taking the rectal specimen. RESULTS: Bacterial growth was analyzed in 500 consecutive patients. In 26 patients the baseline urine sample revealed bacterial growth consistent with contamination. Rectal swab cultures yielded CRO in 104 cases (21 %), of which 92 (88.5 %) were E.coli. Other CRO included Klebsiella pneumoniae, Pseudomonas sp., Morganella morganii, Comamonas, and Stenotrophomonas maltophilia. The CRO were most commonly sensitive to imipenem (100%), ticarcillin/clavulanate (99%), and piperacillin/tazobactam (97%), with high rates of resistances to all other commonly used antibiotics. Bacterial growth was found in 12 of 403 (3%) post-biopsy urine cultures, including 4 (1%) CRO. This growth was not affected by pre-TRUSBx antisepsis. Infectious complications (fever, urinary tract infection or sepsis) occurred in 19 patients (3.8%), including 5/104 (4.8%) of patients with and 14/396 (3.5%) without CRO in the rectum (p 0.05). CONCLUSIONS: CRO are commonly found in the rectum of patients undergoing TRUSBx, but only a very small fraction of patients harboring these bacteria develop infectious complications. The sensitivity data in this trial would suggest imipenem, ticarcillin/clavulanate or piperacillin/tazobactam as appropriate second-line antibiotics for more effective prophylaxis in high risk patients or for treatment of post-biopsy infections. A further line of study will be to investigate the efficacy of antibiotic prophylaxis tailored to the specific bacteria identified on a pre-biopsy rectal swab.