Correlation Between Detection of Extended-spectrum β-lactamases Phenotype and CTX-M-enzymes Genotype
LIU Wen-en,CHEN La-mei,GUO Jing-jing,et al.(Department of Clinical Laboratory,Xiangya Hospital,Central South University,Changsha 410008,Hunan)
Objective To investigate the correlation between phenotypic confirmatory by double disc test and genotype of CTX-M-enzymes detected by multiplex polymerase chain reaction(PCR).Methods ESBLs producing isolates were confirmed by means of phenotypic confirmatory tests as recommended by the CLSI/NCCLS.Multiplex PCR was used to determine the genotype of the CTX-M enzymes.Results Of the 233 clinical isolates of multidrug resistant gram-negative bacilli,136 ESBL-producing clinical strains were identified,99 isolates were confirmed to possess blaCTX-M genes by multiplex PCR.The rate of ESBLs-producing strains carrying CTX-M-type β-lactamases was 72.8%.According to the results of genotype of CTX-M-enzymes,retrospective analysis of the data of phenotypic confirmatory was conducted. The results suggested that none of CTXM-producing isolate was detected by CAZ and CAZ/Clavulanic acid;72.8% CTX-Mproducing isolates were detected by CTX and CTX/ Clavulanic acid;41.7% CTX-M-producing isolates were detected by both of double-disk methods simultaneously.Conclusions The phenotypic confirmatory tests for CTX-M enzymes can be detected only by CTX and CTX/ Clavulanic acid effectively.Using both CTX,CTX/ Clavulanic acid and CAZ,CAZ/ Clavulanic acid simultaneously can reduce the missing rate of ESBLs.
【CateGory Index】： R450