Clinical Predictors of Fluoroquinolone-Resistant Escherichia coli in Transrectal Ultrasound-Guided Prostate Biopsy: Insights for Tailored Prophylaxis.

Objectives: To identify clinical predictors of fluoroquinolone-resistant Escherichia coli colonization and evaluate their usefulness in guiding personalized antibiotic prophylaxis for patients undergoing transrectal ultrasound-guided prostate biopsy.

Methods: A retrospective analysis was conducted on 539 patients who underwent biopsy between January 2015 and March 2023 at a high-volume referral center. Clinical data, including demographic, biochemical, and pathological parameters, were extracted. Patients were stratified into high- and low-risk groups based on the Japanese Urological Association's risk classification. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of fluoroquinolone-resistant E. coli.

Results: Fluoroquinolone-resistant E. coli was detected in 17.1% of patients. The prevalence increased significantly over time, from 14.1% in the earlier period (2015-2019) to 20.9% in the later period (2019-2023) (p = 0.04). Multivariate analysis identified elevated C-reactive protein greater than 0.09 mg/dL and the use of steroid or immunosuppressive therapy as independent predictors of fluoroquinolone-resistant E. coli. In high-risk patients, elevated HbA1c greater than 5.9% was also a significant predictor. Notably, patients with fluoroquinolone-resistant flora had significantly lower rates of prostate cancer detection, particularly among low-risk individuals (52.1% vs. 75.7%, p < 0.01).

Conclusions: Elevated C-reactive protein and immunosuppressive therapy are strong clinical predictors of fluoroquinolone-resistant E. coli colonization. These factors should be integrated into pre-biopsy assessment to guide selective rectal swab testing and tailor prophylactic strategies, thereby enhancing patient safety and reducing antibiotic resistance.