Title: Mechanism and dissemination of macrolide resistance in Streptococcus pneumoniae isolates from Shanghai
Abstract: ObjectiveTo analyze the mechanism of macrolide resistance and characterize the dissemination of resistance gene in Streptococcus pneumoniae isolates from Shanghai.MethodsAntibiotic susceptibility was determined by E test method or Kirby-Bauer disk diffusion test according to National Committee for Clinical Laboratory Standards.Macrolide-resistant phenotypes were classified using a double disc test with erythromycin and clindamycin.The ermB,mefA,mefE,msrD and intTn genes were amplified by PCR.The dissemination of resistant gene was characterized by transformation. ResultsOf the 118 erythromycin-resistant isolates,only 5.9% were susceptible to clindamycin,72.7% were non-susceptible to penicillin.Amoxicillin-clavulanate and levofloxacin showed good activity against most of the erythromycin-resistant isolates.The prevalence of resistant genes was identified as follows: ermB,88.1%;mefE,50%;msrD 50%;mefA 0%;and transposon integrase gene(intTn) 97.5%.The most common macrolide resistance phenotype was cMLS_(B) phenotype(94.1%),which had ermB(+)mefE(+)msrD(+)intTn(+) and ermB(+)mefE(-)msrD(-)intTn(+) genotype patterns.About 5.9% of the isolates showed M phenotype,which had ermB(-)mefE(+)msrD(+)intTn(+) pattern.The resistant gene can be disseminated by transformation.ConclusionsIn Shanghai,ermB-mediated cMLS_(B) is the most prevalent phenotype among erythromycin-resistant S.pneumoniae isolates.There is a tendency that the mefE gene derived from S.pneumoniae can spread rapidly.Transposon may play an important role in the dissemination of resistance genes in S.pneumoniae.
Publication Year: 2006
Publication Date: 2006-01-01
Language: en
Type: article
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Cited By Count: 2
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