肺炎链球菌红霉素相关耐药基因与耐药表型的关系

目的:了解肺炎链球菌(Streptococcuspneum oniae,SP)临床分离株红霉素耐药基因的流行状况及和耐药表型的关系。方法:对住院儿童分离到的43株肺炎链球菌进行红霉素药敏试验,并用PCR法检测与红霉素耐药相关的红霉素核糖体甲基化酶基因(ermB)、主动外排转运基因(mefA)。结果:43株肺炎链球菌红霉素药敏试验40株耐药(占93%),3株敏感。红霉素ermB基因总检出率为76.7%(33/43),mefA基因总检出率为23.3%(10/43)。3株红霉素敏感的肺炎链球菌均未检出ermB基因和mefA基因;40株红霉素耐药肺炎链球菌ermB基因和mefA基因的PCR检出率分别为82.5%(33/40)和25%(10/40)。共有35株肺炎链球菌检出ermB基因或/和mefA基因,其中单独携带ermB基因的耐药表型为25株(占71.4%);单独携带mefA基因的耐药表型2株(占5.7%);同时携带ermB基因和mefA基因的耐药表型8株(占22.9)%。结论:ermB基因和mefA基因同时表达或单独表达均可导致红霉素耐药,ermB基因表达是儿童肺炎链球菌对红霉素耐药的主要原因,mefA基因表达是造成对红霉素耐药的次要原因。红霉素已不是治疗肺炎链球菌的有效药物。

Research of erythromycin resistance phenotype and resistance gene in sreptococcus pneumoniae

Objective:To investigate the prevalence of erythromycin resistance gene ermB and mefA and the relationship of drug resistance and gene in sreptococcus pneumoniae. Methods:Forty three strains of S.pneumoniae were collected from respiratory system infected children Erythomycin sensitivity test was done by using MIC method. The erythromycin resistance gene ermB and mefA were detected by PCR.Results: In all forty three strains,forty were erythromycin resistant(93%),three were erythromycin sensitive. The total detection rate of erythromycin resistance gene ermB and mefA were 76.7%(33/43) and 23.3%(10/43) respectively .There were neither gene ermB nor gene mefA in 3 erythromycin-sensitiveness S.pneumoniaes.The detection rate of gene ermB was 82.5% in 40 strains,which of gene mefA was 25% in 40 strains.The erythromycin resistance gene ermB or mefA were detected in 35 of the 43 strains.The total detection rate of erythromycin resistance gene was 81.4%.There were 25 strains in which gene ermB existed lonely in the 35 erythromycin resistance strains,there were 2 strains in which gene mefA existed lonely in the 35 erythromycin resistance strains. There were both gene ermB and gene mefA in 8 of the 35 erythromycin resistance strains. Conclusion: The erythromycin resistance of S.pneumoniae can be caused mainly by gene expression of ermB or mefA ,but the gene mefA seems to be less important than gene ermB. Obviously the erythromycin isn't useful in treating S.pneumoniae infection.