Caracterización molecular de genes de resistencia a β-lactámicos en aislados bacterianos clínicos de la familia Enterobacteriaceae

Abstract

Infections developed by extended spectrum β-lactamase-producing Enterobacteriaceae (ESBL) are associated with high mortality and morbidity rates in hospital settings due to their ability to hydrolyze β-lactam antibiotics. The objective of this study was to characterize the genes that confer resistance to β-lactams in Enterobacteriaceae obtained from a tertiary hospital in the city of Quito. 153 Enterobacteriaceae were collected and the species was identified with biochemical tests. The study selected the isolates that presented ESBL enzyme production analyzed by the double disk synergy method and the VITEK 2 automated system provided by the hospital. Of the 22 selected isolates, 19 were identified as Escherichia coli and 3 as Klebsiella oxytoca. The ability of the isolates to produce carbapanemase enzymes was determined with the Triton Hodge Test (THT), showing that no isolate had this capacity. The identification of resistance genes used a polymerase chain reaction and used specific primers for each gene encoding ESBL (blaCTX-M, blaTEM, blaSHV) and carbapenemase enzymes (blaKPC, blaIMP, blaVIM, blaNDM). The identification of the allelic variant reported that 11/22 isolates presented the blaCTX-M-15 gene and 4/22 the blaTEM-1 gene. None of the isolates presented genes for resistance to carbapenems. \n\xa0 \nKEYWORDS: allelic variant, bacterial resistance, Enterobacteriaceae, extended spectrum betalactamases (ESBL), resistance genes.