Investigation of the genomic ampD and its mutation from Enterobacter cloacae
ZHAO Hu,TU Wan,FANG Yi,et al. (Department of Clinical Laboratory,Huadong Hospital of Fudan University,Shanghai 200040,China)
Objective To explore the genomic ampD and its mutation sites with high probability from Enterobacter cloacae. Methods The strains of Enterobacter cloacae were isolated from the nosocomial infectious patients in our hospital.The ability and the types of AmpCβproducing-lactamases were comfirmed by the improved Cefotaxime three-dimensional test.The genomic DNA was extracted,and genomic AmpD was amplified by using PCR,then it was ligated into pMD19-T vector and sequenced.Mutation sites were analyzed by comparing with the AmpD sequence of the standard wild-type strains.Results Most parts of the strains contain genomic ampD.Among them,genomic ampD was amplified in all the clinical isolates pruducing durative high expressed AmpCβ-lactamases.The sequences of ampD were successfully obtained;Enterobacter cloacae contains 62 mutation sites,with the probability being over 50%.Conclusion All the strains of Enterobacter cloacae pruducing durative high expressed AmpCβ-lacta-mases contain genomic ampD;the mutation sites with high probability may be the potential cause of pruducing durative-high-expressed AmpCβ-lactamases.