Genotype distribution of plasmid-mediated AmpC β-lactamases, extended-spectrum β-lactamase among Escherichia coli and Enterobacter cloacae isolates in Jiamusi.

Objective To investigate the main genotypes and the epidemic characteristics of plasmid-mediated AmpC beta-lactamases and extended-spectrum beta-lactamases(ESBLs) among Escherichia coli and Enterobacter cloacae isolates in Jiamusi.Methods A total of 127 clinical isolates of nonrepetitive drug-resistant E.coli(81) and E.cloacae(46) were detected by three-dimensional extract test for AmpC β-lactamases and ESBLs.Polymerase chain reaction(PCR) for plasmid-mediated AmpC and ESBLs gene amplification and DNA sequencing was carried out for genotype of the both β-lactamases.Results Among 46 isolates of E.cloacae,producing only AmpC β-lactamases were 10 strains(21.7%),only ESBLs were 13 strains(28.3%),AmpC β-lactamases plus ESBLs were 5 strains(6.5%).Among 81 isolates of E.coli,producing only AmpCβ-lactamases were 16 strains(19.8%),only ESBLs were 31 strains(38.3%),AmpC β-lactamases plus ESBLs were 8 strains(9.9%).In the E.coli,the plasmid-carried ESBLs genotypes were TEM,SHV and CTX-M,and the plasmid-carried AmpC genotype was DHA.In the E.cloacae,the plasmid-carried ESBLs genotype were TEM,SHV and CTX-M,and the plasmid-carried AmpC genotype was DHA.Conclusion This study shows that CTX-M-type and DHA-1-type are predominant genotypes of ESBLs and plasmid-msediated AmpC beta-lactamases among E.coli and E.cloacae in Jiamusi.