我国各地区18所教学医院金葡菌临床分离株杀白细胞毒素基因检测及分子流行病学调查

Prevalence of Panton-Valentine leukocidin gene in Staphylococcus aureus and its molecular epidemiology in 18 teaching hospitals of China

目的研究我国多所医院临床分离金葡菌中杀白细胞毒素(PVL)分布特征及与临床疾病的关系。方法对18所教学医院临床分离809株金葡菌进行PCR检测PVL基因,PVL阳性菌株经纸片扩散法检测MRSA表型,mecA^femB双重PCR确证MRSA基因型,并对PVL阳性的MRSA进行SCCmec分型,脉冲场凝胶电泳(PFGE)法对PVL阳性的MRSA进行同源性分析。结果809株金葡菌中58株(58/809,7.2%)携带PVL基因。沈阳检出率较高,其次为武汉,与其他医院差异有统计学意义(P<0.05);PVL阳性的MRSA15株(15/407,3.5%),MSSA43株(43/402,11.1%),差异无统计学意义(P>0.05);PVL阳性的门诊菌株7.9%(5/63),住院6.9%(53/746),差异无统计学意义(P>0.05)。PVL阳性的MRSA经SCCmec分型,Ⅱ型3.8%(2/53),Ⅲ型4.7%(12/258),未分型1.0%(1/104),差异无统计学意义(P>0.05)。PVL阳性的MRSA经PFGE后,A克隆株73.3%(11/15);B克隆株13.3%(2/15);C克隆株6.7%(1/15);D克隆株6.7%(1/15),差异有统计学意义(P<0.05)。结论PVL可以引起严重感染,及时进行检测并做同源性分析,采取有效的措施控制医院感染的暴发。

Objective To investigate the distribution of Panton-Valentine leukocidin （PVL） gene in S. aureus, and the clinical implication of PVL gene. Methods PVL gene was detected by PCR in 809 strains of S. aureus isolated from 18 teaching hospitals. Methicillin-resistant S. aureus （MRSA） carrying PVL gene phenotype was determined by K-B method, and were confirmed by rnecA-fernB double PCR. SCCmec typing was confirmed by multiplex PCR. Pulsed-field gel electrophoresis （PFGE） with Sinai digestion of chromosomal DNA was used for the genotyping analysis. Results We identified PVL gene in 58 isolates. The average prevalence of PVL was 7.2% in S. aureus isolates. The prevalence of PVL gene in MRSA （15/407, 3.5%） was lower than in MSSA （43/402, 11. 1%）. The difference was not statistically significant （P〉0.05）. The prevalence of PVL gene was significantly higher in the isolates from outpatients than that from inpatients （P〉0. 05）. SCCmec typing was conducted for 15 PVL-positive MRSA isolates. The prevalence of SCCmec Ⅱ, SCCmec Ⅲ and nontypable strains accounted for 3.8%, 4.7%, and 1.0% respectively （P〉0.05）. PVL-positive MRSA isolates were further typed by PFGE. The most common PFGE type was type A and its related subtypes （73.3 % ）, followed by type B （13.3 % ）, C （6.7 % ）, and D （6. 7 % ）, Conclusions PVL toxin can result in serous diseases. It is necessary to identify the genotype timely for adequate control of PVL-positive MRSA outbreak in hospital.