ABSTRACT
Objective To investigate the antibiotic resistance and molecular epidemiology character of ?-lactamase producers among clinical isolates of Citrobacter freundii.Methods Four strains of Citrobacter freundii were detected by K-B susceptibility method and three-dimensional test.The ?-lactamase gene was identified by polymerase chain reaction(PCR) and sequencing.Results The No.29 strain of Citrobacter friundii was multiple-drug-resistant and proved to produce CMY,DHA type AmpC,TEM and SHV type of extended-spectrum ?-lactamases(ESBLs).The sequencing of corresponding DNA revealed 97% identities of the CMY-2 amino acid sequence.It was a new type of cephalosporinase.Conclusion A novel strain of Citrobacter friundii with CMY type AmpC,DHA type AmpC,TEM and SHV type ESBLs has been found in southern China and it is multiple-drug-resistant.