Antibiotic Resistance Rates of Colistin Resistant Gram-Negative Bacteria and a Comparison of Etest and VITEK2 in Evaluation of Colistin Resistance

In the present study we aimed to investigate antibiotic resistance rates in colistin resistant bacteria; and also to compare two methods (Etest and VITEK 2) for detection of colistin resistance. A total of 56 strains were defined as colistin resistant according to VITEK2. Among the 56 colistin resistant strains, only 40 (71.4%) of them were defined as resistant according to Etest method. 34 (85%) out of these 40 strains were identified as K. pneumoniae. The resistance rates were detected for ciprofloxacin, meropenem and ceftazidime as 100%, 97.5% and 95% respectively for all colistin resistant strains. Among the 16 colistin susceptible strains, the resistance to ciprofloxacin, meropenem and ceftazidime were found as 100%, 87.5% and 81.25 respectively.