Phenotypic and Genotypic Identification of Carbapenem-Resistant Klebsiella pneumoniae and Determination of Antibiotic Susceptibility

Aim: Characterization of carbapenemase genes in K. pneumoniae isolates was aimed. Patients and Methods: In this study, 95 multi-drug resistant K. pneumoniae from samples between July 2016 and December 2017, were included. The MIC of meropenem, tigecycline and colistin were determined by Vitek 2, Etest and Broth Microdilution Methods (BMD). The Categorical agreement (CA), Very Major Error (VME) and Major Error (ME) rates were calculated and evaluated. The mcr-1, blaOXA-48, blaOXA-181, blaNDM-1, blaVIM, blaIMP genes were detected. Results: The meropenem resistance were determined in the isolates by BMD, Vitek 2 and Etest are respectively; as 70.5%, 87.4%, 81.1%. According to the BMD method, the rates of CA, VME and ME were determined by Vitek 2; Etest as 69.5%, 4.8% and 20 %; 70.5%, 1.5 % and 0 % respectively. It was determined that our isolates showed the highest sensitivity to tigecycline. The CA rates were determined by Vitek 2 and Etest for tigecycline as 70.5% and 95.8%. The ME rate determined by Vitek 2 was above the acceptable limit of 7.6%. The colistin resistance was 48.4% via BMD. The CA; VME; ME ratios determined by Vitek 2/Etest were 86.3%/72.6%; 17.4%/50%; 10.2%/6.1% respectively. In the isolates, predominantly blaOXA-48 (93.7%) was detected. blaOXA-48 was detected alone in 56. isolates and together with blaOXA-181 genes in 33 isolates. Lower colistin MIC levels were found in the only OXA-48 positive strains than in isolates together with OXA-181. The blaNDM-1 gene was investigated in 3.2% of the isolates. PCR and carbapenemase combined disc results were found to be compatible in 91.3% of the isolates. Conclusion: The blaOXA-48 gene region remains prevalent. In addition, comprehensive identification of the real prevalence and resistance dynamics of blaOXA-48-like gene regions will contribute to the development of national carbapenemase surveillance policies.