The investigation of the VIM, IMP, NDM-1, KPC and OXA 48 enzymes in bacteria which belong to carbapenem resistant Enterobacteriaceae

Bacteria belonging to Enterobacteriaceae family are the most frequently isolated bacteria from clinical specimens, and due to their high resistance, there are problems in terms of treatment. This study was carried out to show the resistance profiles in enterobacteria against carbapenems which are a group of antibiotic with wide spectrum. The study was carried out with 95 Enterobacteriaceae strains isolated from various samples sent to our laboratory. Among the isolates, 60 were resistant to imipemen, meropemen and ertapenem, 20 were resistant to imipenem or ertapenem, and 15 were sensitive to all three drugs. The activity of carbapenemase was investigated phenotypically with Modified Hodge test (MHT) and chrome agar, and genotypically with PCR. The study included 41 (43.2%) K.pneumoniae, 27 (28.4%) E.coli, 13 (13.7%) P.mirabilis, 10 (10.5%) E.cloacae, 1 (1.1%) each S.marcescens, K.oxytoca, P.stuartii, and E.aerogenes strains. Out of the strains, 48 (50.5%) were determined positive and 26 (27.4%) negative with MHT. With chrome agar, 69 strains (72.6%) were found positive and 26 (27.4%) negative. Forty-five of 48 MHT positive strains were chrome agar positive and three were chrome agar negative. The sensitivities of the MHT and chrome agar were 78.95% and 100%, respectively. During the study, the presence of KPC (1-10), OXA48, VIM (1-13), IMP (1-22), and NDM-1 enzymes was investigated genotypically. Carbapenemase gene was found positive in 57 (60%) strains and OXA48 (50 strains, 87.7%) was determined as the most frequent gene. NDM-1 was detected in 6 (10.4%) and VIM in 2 (3.5%) of the isolates. IMP and KPC gene regions were not detected. As the result, chrome agar was found to be a practical and useful method in determining the activity of carbapenemase. MHT is a time-consuming and troublesome method and due to its low sensitivity in detecting NDM-1 carbapenemase positive strains, this method should be used carefully. Key words: Enterobacteriaceae, carbapenem, Modified Hodge test, chrome agar, VIM, NDM1, OXA 48