47株金黄色葡萄球菌临床血流感染分离株的基因分型研究

Genotyping on 47 Staphylococcus aureus strains associated with bloodstream infection

目的研究金黄色葡萄球菌临床血流感染分离株的分子流行病学特征。方法收集2006年1月至2008年12月解放军总医院分离的临床血流感染金黄色葡萄球菌菌株（共47株），标本来源均为患者静脉血。采用琼脂稀释法检测所有菌株对多种抗生素的耐药性，PCR方法检测pvl毒素基因，DiversiLab^TM Rep．PCR分型系统分析菌株的同源性；对耐甲氧西林金黄色葡萄球菌（MRSA）进行葡萄球菌染色体mec（SCCmec）分型以及ST239型别的快速筛查；综合分型和药敏试验结果，挑选部分代表菌株进行多位点序列分型（MLST）。结果47株血流感染金黄色葡萄球菌中，pvl基因检出率为4．3％。MRSA占51．1％，MRSA均为SCCmecⅢ型菌株；Rep．PCR分为A～L共12个型，其中A型为最主要的型，共22株（46．8％），所有的MRSA均属于A、B两型。结论47株临床血流感染金黄色葡萄球菌中的MRSA绝大部分为多重耐药克隆ST239．MRSA．SCCmecⅢ型。

Objective To investigate the molecular epidemiological characteristics of Staphylococcus aureus associated with bloodstream infection in hospital. Methods 47 Staphylococcus aureus strains isolated from bloodstream in PLA General Hospital were collected from January 2006 to December 2008. Susceptibility of the strains to 11 antimicrobial agents was detected and DNA homology of them was analyzed with Rep-based DiversiLab^TM Microbial Typing System. Panton-Valentine leukocidin （PVL）gene was determined by PCR. For methicillin-resistant Staphylococcus aureus （MRSA） strains, the genotypes of SCCrnec were determined and ST239 clone was screened with multiplex PCR. Multilocus sequence typing （MLST） was used to determine the STs of the selected isolates. Results In the 47 Staphylococcus aurcus isolated from blood, methicillin-resistant strains accounted for 51.1%,all belonged to SCCmecⅢ type,with only 2pvl gene positive strains identified. 12 different patterns （A-L） were found among 47 strains with Rep-PCR. All MRSA strains clustered in the A and B subtypes. Conclusion Most MRSA strains isolated from blood in PLA General Hospital belonged to ST239-MRSA-SCCmec Ⅲ clone. DiversiLabTM Microbial Typing System could provide a rapid and effective method to investigate the molecular epidemiological characteristics of Staphylococcus aureus in the hospital settings.