Detection of ESBLs and AmpC enzyme in Cefoxitin-resistant Klebsiella pneumoniae and analysis of drug-resistant genotype

Objective To understand the producing of ESBLs and AmpC -lactamase of Klebsiella pneumoniae and the drug-resistant phenotype characteristics of AmpC enzyme in Taizhou. Methods Bacteria were identified with VITEK-AMS60. ESBLs were detected with the confirmatory test recommended by CLSI. Positive strains harboring AmpC enzyme were screened with cefoxitin disk diffusion. Methods AmpC enzyme was confirmed by a three-dimensional test and genotype was differentiated by PCR-sequencing. Results In the 86 isolates of Klebsiella pneumoniae insensitive to cefoxitin, the detection rates of ESBLs and AmpC enzyme were 88.37% and 77.91% respectively. Among them, 47.67% produced both ESBLs and AmpC enzyme, 40.70% produced only ESBLs and 30.23% produced only AmpC enzyme. The drug-resistant genotypes for AmpC-positive strains were DHA-1(62 isolates) and ACT-1(5 isolates). Conclusion The detection rate for Klebsiella pneumoniae haboring ESBLs and AmpC enzyme was high in Taizhou and AmpC enzyme mainly belonged to DHA-1 genotype.