Introduction: Fluoroquinolones have been commonly used for antibiotic prophylaxis before transrectal ultrasonography guided prostate biopsy (TRPB). The possession of fluoroquinolone-resistant E. coli (QREC) in rectal flora is thought to be a risk factor off ebrile complications following TRPB and culture-based antimicrobial selection was recommended for patients with QREC. Amikacin (AMK) is promising agent because of potent antimicrobial activity against QREC and excellent permeability to the prostate tissue. We evaluated the efficacy of adjuvant AMK to oral levofloxacin (LVFX) as prophylaxis for TRPB.
Methods: From October 2016 to September 2021, a total of 426 patients who underwent TRPB were enrolled. Prior to TRPB, rectal swabs were cultured. Isolated E. coli was determined as QREC when their minimum inhibitory concentration (MIC) of LVFX was 4 µg/mL or above according to the breakpoint MIC by the Clinical and Laboratory Standards Institute criteria.
As antimicrobial prophylaxis for all patients, a single oral 500mg of LVFX was administered two hours before TRPB. For patients with QREC in rectal flora (QREC carriers), single dose of 400mg of AMK was added intravenously before TRPB. All biopsies were carried out through a standard 12-core approach with local periprostatic anesthesia. Additional targeted biopsy was done in some patients. The patients were followed up for 4 weeks after TRPB and febrile infective complications were recorded.
Results: Forty QREC carriers (9.4%) were detected in this study. All of E.coli isolated from QREC carriers were sensitive to AMK. A total of 10 patients (2.3%) suffered from febrile complications following TRPB. Three of them were QREC carriers and the others were non-QREC carriers. The incidence of febrile complications following TRPB among QREC carriers was higher than that of non-QREC carriers (7.5%, 3/40vs 1.8%, 7/386; p=0.058, Fisher's exact test).
Conclusions: The adjuvant AMK to oral LVFX was not so effective in QREC carrier, although all strains of isolated E. coli from QREC carrier were sensitive to AMK. We concluded the culture-based antimicrobial prophylaxis had a limitation of complete prevention of febrile complications following TRPB.
While escalation or further augmentation of prophylactic agents will reduce febrile complications in a short time, these will accelerate the increase of resistant bacteria in a long time and violate the principal of good antibiotic stewardship. For resistant strain carriers, the switching to transperieal prostate biopsy should be considered.