Genotypic and phenotypic identification of the carbapenem resistant enterobacteriaceae strains

Emergence of carbapenem-resistant Enterobacteriaceae is increasingly reported worldwide and cause therapeutic problems in health care facilities. Carbapenems are often considered as a last therapeutic choice for the treatment of life threatining of infections due to multidrug-resistant Gram-negative rods. For that reason Carbapenem resistance is extremely important. In the present study, It has been intended to examine the genotypic and phenotypic properties of the carbapenem resistant Enterobacteriaceae strains that are isolated from our hospital and the genetic mechanisms that cause the carbapenem resistance. A total of 43 carbapeneme resistant strains have been included in this study.Identification and antibiotic susceptibility tests were performed by Vitek-2 system.Carbapenem MIC values were also studied by E-test. Modified Hodge Test (MHT) and MBL E test were used for phenotypic detection, and PCR, Multipleks PCR (hyplex® SuperBug ID), by using specific primers for the detection of bla OXA-48 , bla KPC , bla NDM 1 and bla VIM type carbapenemases with specific primers were performed. Carbapenemase production was demonstrated by modified Hodge test and 81.4 % of isolates were positive. Seven isolates of 43 were positive for blaOXA-48 and one for blaNDM-1 and there wasn't any positivity for the others. With PCR results as reference, PCR compliance with phenotypic tests were compared. There was compatibility between OXA 48 positivity and MHT ( p < 0,05) and MBL E test between NDM-1 resistance gene. Antimicrobial susceptibility testing showed that although carbapenem-non-susceptible strains exhibited high resistance rates to other antimicrobial agents. The rate of colistin resisctance were 11.6 %.An early and quick identification of carbapenemase-producing enterobactericeae, is mandatory to prevent the spread of these highly resistant pathogens.