English

Abstract

Testing MIC of Vancomycin for all staphylococcal isolates is mandatory according to the current CLSI guidelines and this will considerably increase the cost of culture and sensitivity testing. This study is an attempt to re-consider the utility of the conventional disc diffusion method for cost-effective testing in resource poor settings. MATERIALS AND METHODS: Thirty coagulase positive and twenty eight coagulase negative staphylococci from various clinical samples have been randomly tested for minimum inhibitory concentration along with the Kirby Bauer disc diffusion method for Vancomycin over a period of five months. RESULTS: Susceptibility results of all the 58 isolates tested have been identical by both disc diffusion and HiComb MIC methods. Out of 58 isolates, 57 (98.26%) staphylococci have been sensitive to vancomycin by Kirby Bauer disc diffusion method as well as by the MIC testing method. The MICs of the susceptible strains have been <2 µg/mL. One isolate, a coagulase negative staphylococcus, has been tested to be resistant to vancomycin by both the methods with an MIC of 32 µg/mL SUMMARY: In our study of staphylococcal isolates from various clinical samples, there is overt significant concordance between disc diffusion and MIC testing methods in the routine susceptibility testing of vancomycin. CONCLUSION: Kirby Bauer disc diffusion method may still be of utility for routine testing of vancomycin susceptibility except for few cases especially in resource poor settings.