Antimicrobial Susceptibility Testing for Escherichia coli Strains to Fluoroquinolones, in Urinary Tract Infections

Background: Urinary Tract Infect ions (UTls) are one of the most common infectious diseases diagnosed all over the world . Meanwhile most episode of UTls are caused by Escherichia coli (up to 85%) and frequently tluoroquinolones are preferred as initial agents for empiric therapy of UTIs. Widespread use of tluoroquinolones has resulted in an increa sing incidence of resistance these agents all over the world. The aim of this study was to assess, susceptibility of Escherichia coli strains from UTI patients against common tluoroquinolones. Methods: Antimicrobial susceptibility testing was determined by disk agar diffusion (DAD) and Minimal Inhibitory Concentration methods as described by the National Corrunittee for Clinical Laboratory Standards (NCCLS). Results: One hundred sixty four clinical isolates of E. coli were collected by urine cultures from patients with UTI. The extent of resistant to nalidixic acid, ofloxacin, nortloxacin and ciprotloxacin, by disk diffusion method was 49.3%,44.5%,41.4% and 40.2%, respectively. Resistance to ciprotloxacin by MIC method was 42.1%. Conclusion: This study represents high level resist ant of E. coli isolates from UTI patients. It is becau se of inappropriate and incorrect administration of antimicrobial agents in blind cases. This problem remarks significance of performing antimicrobial susceptibility testing before empiric antibiotic therapy. To overcome this problem use of unnec essary antibiotics therapy should be limited.