Detection of beta-lactam antibiotic resistance in aquatic Enterobacteriaceae isolates

Abstract

Abstract Production of the beta-lactamase enzymes is the primary resistance mechanism caused by unconcious consumption of the beta-lactam group of antibiotics in Enterobacteriaceae. Combined disc tests were performed for extended-spectrum beta-lactamase (ESBL) confirmation (n = 15) and class C beta-lactamase (AmpC) confirmation (n = 6) after the disc diffusion test was applied in a total of 27 Enterobacteriaceae strains from Western Black Sea, Lake Manyas and Lake Iznik. Plasmid-mediated blaTEM, blaSHV, blaCTX-M , blaIMP genes, CIT, MOX, FOX gene groups and chromosomal blaAmpc gene of E. cloacae were investigated using the polymerase chain reaction (PCR). Three E. coli strains were shown to produce ESBL, while one E.coli and three E. cloacae strains were confirmed for AmpC production by disc tests. blaTEM (n = 2), blaSHV (n = 4), blaCTX-M (n = 2), blaTEM + blaSHV (n = 1), blaCTX-M + CIT (n = 1), blaSHV + CIT (n = 1) genes and/or gene groups were detected in 11 E. coli isolates; while blaSHV (n = 3) was observed in three Klebsiella strains (two K. oxytoca and one K. pneumoniae). With this study, the aquatic environments of Turkey were proved to be the reservoirs of antibiotic-resistance determinants of plasmid-mediated beta-lactamases in environmental wild-type bacteria transmitted by horizontal gene transfer.