Frequency Distribution of Fluoroquinolones-Resistant Enterococcus faecalis Isolates from Patients with Prostatitis in Golestan Province, Iran

Background and Objectives: Enterococcus faecalis is a major cause of bacterial prostatitis, which can increase the risk of developing prostate cancer if mistreated or left untreated. The aim of this study was to evaluate resistance of E. faecalis strains isolated from patients with prostatitis to three fluoroquinolones. Methods: In this cross-sectional study, we collected urine specimen from 164 patients hospitalized in six hospitals in the Golestan Province, Iran. Biochemical and bacteriological tests were carried out to identify E. faecalis strains. Pattern of resistance to ciprofloxacin, levofloxacin and norfloxacin was studied using the agar disk diffusion method (Kirby-Bauer method). The broth microdilution test was performed to determine minimum inhibitory concentrations (MICs) of fluoroquinolones according to the CLSI M100-S25 (2015) criteria. Results: Of 164 isolates, 39 (23.8%) were identified as E. faecalis. Frequency of resistance to ciprofloxacin, norfloxacin and levofloxacin was 12.8%, 12.8% and 2.6%, respectively. The MIC90 of ciprofloxacin against the isolates was 4 μg/ml, which was 4-fold lower than that of norfloxacin (MIC90=16μg/ml) and 2-fold lower than that of levofloxacin (MIC90=8μg/ml). We found no significant difference between the isolates in terms of resistant to the fluoroquinolones (P>0.01). Conclusion: Our results show that E. faecalis is one of the most common causes of bacterial prostatitis, and fluoroquinolones are still effective for treating the infection despite the reports of fluoroquinolones resistance in Iran. Moreover, levofloxacin may be a more suitable and effective antibiotic than ciprofloxacin and norfloxacin for treatment of this infection.