Efficacy of adjuvant amikacin combined with oral levofloxacin as prophylaxis for transrectal prostate biopsy in patients harboring fluoroquinolone-resistant Escherichia coli in rectal flora.

PURPOSE

Fluoroquinolones (FQs) are commonly used as antibiotic prophylaxis before transrectal ultrasonography-guided prostate biopsy (TRPB). The presence of FQ-resistant E. coli (QREC) in the rectal flora is thought to be a risk factor for febrile complications following the TRPB, and culture-based antimicrobial selection is recommended as prophylaxis for patients with QREC. Amikacin (AMK) is a promising prophylactic agent because of its potent antimicrobial activity against QREC and excellent permeability of the prostate tissue. We evaluated the efficacy of adjuvant AMK in combination with oral levofloxacin (LVFX) as an antibiotic prophylaxis for TRPB.

METHODS

Between October 2016 and September 2024, 531 patients with E. coli isolated from rectal swab cultures were enrolled. Patients with diabetes, urinary tract infections, or those on immunosuppressive agents were excluded. Rectal swabs were cultured prior to TRPB. Isolated E. coli was determined as QREC when their minimum inhibitory concentration (MIC) of LVFX was 4 μg/mL or above. As antimicrobial prophylaxis for all patients, a single oral 500 mg of LVFX was administered 2 h before TRPB. For patients with QREC, AMK 400 mg was administered intravenously before the TRPB. The patients were followed up for 30 days after the TRPB and febrile infective complications were recorded.

RESULTS

Fifty-nine QREC carriers (11.1%) were identified. All QREC were sensitive to AMK. Eleven (2.1%) patients experienced febrile complications after TRPB. Four 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 among non-QREC carriers (6.8%, 4/59 vs 1.5%, 7/472; p = 0.025, Fisher's exact test).

CONCLUSIONS

Infection control with an AMK adjuvant to oral LVFX in QREC carriers had limitations, although all QREC were sensitive to AMK. We concluded that culture-based antimicrobial prophylaxis has limitations in the complete prevention of febrile complications following TRPB. While escalation or further augmentation of prophylactic agents will reduce febrile complications in the short term, it will accelerate the increase in resistant bacteria in the long term and violate the principles of good antibiotic stewardship. For resistant strain carriers, switching to transperineal prostate biopsy should be considered.