Studies on drug resistance genes among 49 strains of extended-spectrum beta-lactamase-producing bacteria / 中华检验医学杂志

ABSTRACT

Objective To investigate the drug resistance genes of extended-spectrum beta- lactamase-producing bacteria in 49 strains.Methods Extended-spectrum ?-lactamase -producing strains were detected by the disc diffusion test.The techniques of polymerase chain reaction,sequence analysis, pulsed-field gel electrophoresis were used to analyze the genotype and homology of extended-spectrum ?- lactamase-producing strains.Results The incidence of ESBL-producing strains from E.coli,K pneumoniae,K oxytoca,was 20% in 2000,and 40% in 2003.Among the 49 ESBLs producers the most common genotype was CTX-M-14( n=33).The others were CTX-M-3,CTX-M-9,CTX-M-12,CTX-M-15, CTX-M-24 and SHVSa.Both two CTX-M subtypes,CTX-M-3 and CTX-M-14,were detected in one strain. However,4 ESBL-producing strains confirmed by phenotype remained untyped.The results showed that the ESBLs producers were not closely related,except for two strains of E.coli and two strains of K.pneumoniae which were homgenic respectively.Concolusions The incidence of ESBL-producing strains increases with years.The most common genotype of ESBLs is CTX-M.There is no evidence for epidemiologic spread of ESBL-producers by pulsed-field gel electrophoresis.