ABSTRACT
OBJECTIVE:To study the characteristics of ceftazidime-resistant?-lactamase produced by Escherichia coli.METHODS:The types of2strains of drug fast?-lactamase produced by Escherichia coli were determined initially by K-B slip diffusion method and ampholine electrophoresis method;The plasmid was extracted by alkaline lysis and the PCR ampli?fication and sequencing were conducted;?-Lactamase was counter-extracted by saturated ammonium sulfate,filtrated by Sephadex G-75gel and purified by DE-52anion exchange chromatography;The molecular weight of which was determined by SDS-PAGE and the enzyme kinetics parameters of?-lactamas were determined by ultraviolet spectrophotometry.RE?SULTS:The2strains produced a super-broad spectrum?-lactamase(CTX-M-1V)with isoionic point at8.7and the molecular weight at29kDa,which can hydrolyze cefotaxim and aztreonam but imipenem and which was sensitive to sulbactam(IC 50 =94nmol/L)and tazobactam(IC 50 =5nmol/L).CONCLUSION:CTX-M-1V is a CTX-M type super-broad spectrum?-lactamase sensitive to suppressants.