Effectiveness of Fosfomycin Tromethamine Prophylaxis in Preventing Infection Following Ultrasound-guided Prostate Needle Biopsies: Results from a Large Canadian Cohort.

BACKGROUND: Rates of infection following ultrasound-guided transrectal prostate needle biopsy (TRUSPB) are increasing. We aimed to evaluate the effectiveness of fosfomycin tromethamine (FMT) prophylaxis in preventing post-TRUSPB infectious complications.

METHODS: This nested case-control study included patients who underwent TRUSPB in a Canadian tertiary care hospital, and developed post-TRUSPB bacteremia or urinary tract infections. Four prophylaxis periods included: i) ciprofloxacin, low-resistance period (CIPRO-LOW), 2002-2009; ii) ciprofloxacin, high-resistance period (CIPRO-HIGH), 2010-October 2013; iii) oral FMT, one dose (FOSFO1), December 2013-September 2015; and iv) oral FMT, two doses (FOSFO2), October 2015-June 2016. Incidence rates of the infection were calculated.

RESULTS: TRUSPB (n=9,527) resulted in urinary sepsis (n=138; 58% with bacteremia). The incidence rates were 1.8% (CIPRO-HIGH), 3.5% (FOSFO1; p=0.004 vs. CIPRO-HIGH), and 2.7% (FOSFO2; p=0.19 vs. CIPRO-HIGH). Although Escherichia coli remained the predominant pathogen with fosfomycin-based regimens, the proportion of infections caused by Klebsiella spp. was higher (20/66; 30.3%) than that by ciprofloxacin-based regimens (2/77; 2.5%; p<0.0001).

DISCUSSION: Independent risk factors for infection were the prophylactic regimen administered, presence of urological comorbidities, and diabetes. FMT was therefore not an effective alternative to ciprofloxacin for preventing post-TRUSPB urinary sepsis.

CONCLUSIONS: These results highlight the need for novel antibacterial prophylaxis approaches.