Molecular characterization of extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella spp. isolates in Mongolia

Background/purpose: The aim of this study was to determine the molecular char- acteristics of b-lactamase genes in extended-spectrum b-lactamase (ESBL)-producing Entero- bacteriaceae isolates from Mongolia. Methods: Fifty-six ESBL-producing Enterobacteriaceae isolates were collected, of which 46 were Escherichia coli ,s even wereKlebsiella pneumoniae, and three were K. oxytoca. Mini- mum inhibitory concentrations for selected antibiotics were tested using the agar dilution method, and the b-lactamase genes were determined using polymerase chain reaction com- bined with sequencing. Pulsed-field gel electrophoresis (PFGE) was used for genotyping all iso- lates, and phylogenetic grouping was performed on ESBL-producing E. coli isolates.