A Controversy in susceptibility testing of V .cholera against ciprofloxacin by disk diffusion and E-test MIC Methods

Introduction and Objectives: Cholera is a major public health threat affecting the poor in developing countries. The objectives of this study is to determine antimicrobial susceptibility pattern of selected isolates of V. cholera and comparison results two susceptibility testing methods including disk diffusion and E-teat MIC against ciprofloxacin.Materials and Methods: A total of 60 selected clinical isolates of V. cholera, V.cholerae were subject of our study.MIC for ciprofloxacin, nalidixic acid, cefixime, ampicillin, erythromycin and tetracyclin were determined by E-test MIC method. In addition of E-test MIC, disk diffusion method used for susceptibility testing against ciprofloxacin.Results: All isolates were susceptible to CFM, AM, TE and SXT and 90% isolates were resistant to NA. Susceptibility testing to erythromycin performed on 28 isolates and all of them were intermediate. Regarding susceptibility testing against ciprofloxacin by MIC method, 45% were susceptible and 55% were intermediate. Among isolates which were susceptible to CIP by MIC Method, only 63% were susceptible and 37% were intermediate by disk diffusion method. Among isolates of V. cholera which were intermediate by MIC Method, 47% were susceptible and 53% were intermediate by disk diffusion method. Our study revealed that there is a controversy in susceptibility testing of V. cholera against ciprofloxacin by disk diffusion and MIC methods and it is recommended MIC method for testing for ciprofloxacin as a gold standard method.Conclusion: Disk diffusion breakpoints for ciprofloxacin are based upon activity against other Enterobacteriacea and it is expected that in vitro definition of susceptibility would not correlate with clinical response. It is concluded that disk diffusion method is not satisfactory for performance of susceptibility against ciprofloxacin, and MIC methods is recommended.

کلیدواژه ها:

V. cholera ، MIC ، Disk diffusion ، Ciprofloxacin