β溶血链球菌中诱导型克林霉素耐药的检测和分析

Detection and analysis of inducible clindamycin resistance of β-homolytic Streplocotoccus

目的了解β溶血链球菌对红霉素及克林霉素的耐药性,探讨红霉素对克林霉素诱导耐药的表型和基因型。方法按CLSI推荐的K-B法测定并判读β溶血链球菌对红霉素及克林霉素的耐药性,用D试验检测红霉素诱导β溶血链球菌对克林霉素耐药的表型,并且用PCR方法确定所检测的菌株是否携带的ermB基因和mefA基因。结果49株红霉素耐药的β溶血链球菌结果显示有35株β溶血链球菌只扩增到ermB基因,有9株只扩增到mefA基因,有3株同时扩增到ermB和mefA基因,有2株没有扩增到ermB和或mefA基因;17株红霉素耐药克林霉素敏感菌株中D试验阳性8株细菌都只扩增到ermB,D试验阴性9株细菌中都只扩增到mefA;红霉素敏感的β溶血链球菌没有扩增到ermB或mefA基因。结论β溶血链球菌的耐药表型与基因型高度一致,临床上可用PCR方法和D试验检测,D试验检测更为简单方便,临床应该用D试验检测β溶血链球菌的iMLS型耐药。

Objective To investigate the phenotypes and genotypes of β-hemolytic streptococcus with inducible clindamycin resistance. Methods The phenotypes of erythromycin resistance were classified by D test with erythromycin and clindamycin agent disci, ermB and mefA genes were detected by PCR. Results Of all β -hemolytic streptococcusstrains, 17 strains were resistant to erythromycin but susceptible to clindamycin, and 8 strains were D test positive in erythromycin resistance but clindamycin susceptibility; In 49 strains of erythromycin resistance, 35 strains were only found ermB gene, with 9 strains of mefA gene, 3 strains both ermB and mefA genes and 2 strains of neither ermB nor mefA gene. 8 positive strains by D-Test were all found ermB and 9 negative strains were all found mefA. Conclusions iMLS resistant phenotypes of β -hemolytic streptococcus can be detected by both PCR and D test method, and the latter be regarded as a routine detection.