Activity of Gemifloxacin against Levofloxacin – and Ciprofloxacin-Resistant Escherichia coli Displaying DNA gyrase Isolated from Patients Admitted to the intensive care unit

Urethritis is a common infection in hospitals, especially in intensive care units(ICUs), whose treatment is difficult today due to increased prevalence of resistant bacteria.The aim of the present study was to determine the resistance pattern to gemifloxacin in fluoroquinolones-resistant Escherichia coli strains possessed DNA gyrase isolated from hospitalized patients in ICUs. In this descriptive cross-sectional study, patients (n = 113) in ICUs were studied. After identifying of E. coli isolates using specific tests broth microdilution test was used in according to CLSI M100-S25(2015) criteria to determine the minimum inhibitory concentration (MIC) of ciprofloxacin, levofloxacin and gemifloxacin. The fluoroquinolone resistance gene (gyrA) was identified using polymerase chain reaction (PCR) with specific primers. In this study, the prevalence of E. coli isolates resistant to ciprofloxacin was reported 35.2%. Determining MIC of gemifloxacin showed that 87.3% of the strains were susceptible to it (MIC, ≤0.25μg/ml), while 53.5% MIC (≤1μg/ml) and 46.5% o (MIC, ≤2μg /ml) of isolates were categorized as susceptible to ciprofloxacin and levofloxacin respectively.The concentration of gemifloxacin, that inhibited 90% growth of isolates (MIC90) was 0.5μg /ml , 8-fold lower than levofloxacin (MIC90=4μg/ml) and 8-fold lower than ciprofloxacin (MIC90=4μg/ml). The study of the polymerase chain reaction on gemifloxacin-resistant isolates confirmed the mutation in serine 83 of gyrA gene. We conclude that not only resistance to fluoroquinolones, but the frequency of gyrA gene in E.coli strains isolated from special hospitalized patients is increasing.