Plasmid-mediated AmpC β-Lactamases Genes in Enterobacter cloacae in Ningbo Area and Preliminary Discovery of a New ACT-1 Subtype:An Epidemic Surveillance

OBJECTIVE To investigate the prevalence and genotype of plasmid-mediated AmpC β-lactamases genes in Enterobacter cloacae strains isolated from Ningbo area.METHODS All isolated E.cloacae strains were subjected by polymerase chain reaction(PCR),and some of the fragments produced by PCR were sequenced and analyzed.RESULTS For 85 strains,the total positive rate of plasmid-mediated AmpC genes was 32.9%,and the positive rates of DHA and ACT-1 genotypes were 29.4% and 3.5%,respectively.CONCLUSIONS The main genotype of plasmid mediated AmpC genes in Ningbo area is DHA,and the second is ACT-1;furthermore,the ACT-1 gene may be a new subtype that worth to be further studied.