Genes of Extended Spectrum ?-Lactamases and AmpC ?-Lactamase from Klebsiella pneumoniae and Klebsiella oxytoca / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To study the phenotypic existence,genetic type and gene transfer of extended spectrum beta-lactamases(ESBLs) and AmpC beta-lactamase from Klebsiella pneumoniae and K.oxytoca. METHODS Disk confirmation test and 3-aminophenylboronic acid(APB) disk potentiation test were used to detect ESBLs and AmpC beta-lactamase.The genetic types of these two kinds of beta-lactamases were examined by gene chip technology and sequence analysis.The transfer of resistance genes was conducted by conjugation. RESULTS From 72 strains of K.pneumoniae and 20 strains of K.oxytoca which were not susceptible to cefoxitin,coexistence of AmpC(beta-lactamase) with ESBLs together was very common,accounted for 54.2% and 75.0%,single ESBLs accounted for 22.2% and 25.0%,respectively.There were 12.5% single AmpC in(K.pneumoniae).DHA type ampC gene and SHV type ESBLs gene were the main molecular types.These genes could be transferred from clinical isolates to recipient E.coli J53. CONCLUSIONS ESBLs as well as AmpC(beta-lactamase) are the most important resistance mechanism in K.pneumoniae and K.oxytoca.The resistance could be transferred through the bacterial conjugation.