Characterization of carbapenemases in Enterobacteriacae

Karbapenemi su antibiotici stabilni prema većini β-laktamaza pa su često jedina terapijska opcija u liječenju infekcija uzrokovanih multirezistentnim enterobakterijama. Sve je češća pojava otpornosti enterobakterija na karbapeneme zbog proizvodnje KPC, VIM, NDM i OXA-48 β-laktamaza. Cilj rada bio je istražiti mehanizme rezistencije na karbapeneme. Izolati su bili prikupljani tokom 2011. i 2012. godine iz različitih bolničkih centara u Hrvatskoj. Testiranje osjetljivosti na antibiotike napravljeno je disk-difuzijskom i MIK metodom. Fenotipska detekcija ESBL enzima napravljena je metodom kombiniranih diskova po CLSI-u, detekcija metalo-β-laktamaza napravljena je pomoću imipenem/meropenem-EDTA disk-difuzijske metode a detekcija KPC enzima pomoću 3-aminofenilboronične kiseline. Detekcija gena rezistencije napravljena je pomoću lančane reakcije polimeraze početnicama specifičnim za ESBL, OXA-48, KPC, IMP, VIM, NDM i plazmidne AmpC -laktamaze. Svi sojevi koji su bili pozitivni na proizvodnju karbapenemaza posjedovali su gene blaESBL i blaampC što predstavlja ozbiljan problem u liječenju bolesti upravo zbog multirezistencije koju pokazuju.Carbapenems are antibiotics that are frequently used to treat infections with multidrug-resistant Enterobacteriaceae because they are not inactivated by most β-lactamases. However, β-lactamase mediated resistance to carbapenems has been reported in Enterobacteriaceae, mostly due to the expression of KPC, VIM, NDM or OXA-48 β-lactamase. The purpose of this research was to clarify the resistance mechanisms to carbapenem antibiotics. The isolates were gathered in several hospital institutions in Croatia. The antimicrobial susceptibility to a wide range of antibiotics was determined by disk-diffusion and MIK test. Detection of ESBLs was done by CLSI confirmatory test, detection of metallo-β-lactamases was done by imipenem/meropenem-EDTA test and detection of KPC enzime was done by 3-aminophenylboronic acid test. The presence of genes encoding β-lactamases was determined by PCR using primers for ESBL, OXA-48, KPC, IMP, VIM, NDM i plasmid-mediated AmpC beta-lactamases. The fact that most of the strain possessed not only blacarb genes but also blaESBL and plasmid-mediated blaampC genes limits therapeutic options