Investigation of carbapenem resistance in enterobacteriaceae species and the presence of the enzymes responsible from resistance

Carbapenems admitted as a significant treatment choose in multi-drug resistant gram-negative bacteria infections. Unfortunately nowadays antimicrobial effectivity of carbapenems gradually have decreased with showing up enzyms which hydrolyze carbapenems. Carbapenemases are β-lactamases have the most powerfull hydrolytic activity. It is reported that carbapenemases KPC, OXA-48, OXA-58 and metallo-β-lactamases as VIM, IMP, NDM are responsible for carbapenem resistance in members of the Enterobacteriacea mostly. In the study it was aimed to investigate carbapenemases gene region responsible for production of carbapenemase enzymes in three members of carbapenem resistant Enterobacteriaceae which commonly isolated as infection agents. The study was performed at Afyon Kocatepe University Hospital between the dates January 2012 and December 2012. A total of 237 strains member of Enterobacteriacea, including 138 Klebsiella pneumoniae, 52 Escherichia coli and 47 Enterobacter spp. isolated from various clinical samples were collected during the study period. Clinical isolates that showed decreased susceptibilty or resistance to any of carbapenem were investigated. Identification of the bacteria and antibiotic susceptibility tests were performed by conventional methods and automated system (Phoenix100, Becton Dickinson Co, Sparks, MD, USA). Polymerase chain reaction (PCR) method were use to detection of the KPC, VIM, IMP, NDM, OXA-58 and OXA-48 gene regions encoding carbapenemase. Strains were isolated from inpatients (75 %) from internal medicine departments, especially from pediatry clinic and isolated from urine samples (n=108), wounds (n=48), blood (n=43), endotracheal aspirates (n=23) and sputum (n=15). Resistance or decreased susceptibility to at least one of ertapenem, imipenem and meropenem were detected in 19 % of isolates (33 K. pneumoniae, 7 E. coli ve 6 Enterobacter spp.). The presence of at least one of gene encoding carbapenemases were detected in 89 % of carbapenem resistant isolates. blaOXA-48 was the most common genes encoding carbapenemase (in 21 K. pneumoniae, 2 E. coli and 3 Enterobacter spp. strains). The other genes were following that blaVIM (19 K. pneumoniae, 2 Enterobacter spp.), blaIMP (10 K.pneumoniae, 1 Enterobacter spp.) and blaNDM-1 (1 K.pneumoniae), respectively. The presence of KPC and OXA-58 genes were not observed in any of isolates. The worldwide spread of Enterobacteriaceae expresing carbapenemases represents a major important treat of global health concern, because therapeutic options are very limited in infections cause by these carbapenemase producers. So defining carbapenem resistant strains is the primary important subject. The results of this study indicate that carbapenem resistance are higher especially in K.pneumoniae strains and OXA-48 was primarly responsible enzymes from carbapenem-resistance, but also it was determined that metallo-β-lactamases were frequent. In addition of these findings NDM-1 carbapenemase producing K.pneumoniae strain was isolated firstly and resistance gene was defined. Key Words: Enterobacteriaceae, carbapenemases, resistance.