沙尘天气气载耐甲氧西林葡萄球菌监测及其REP-PCR指纹图谱分析

目的 了解沙尘天气时空气中葡萄球菌浓度及气载MRSA的遗传多样性,为临床葡萄球菌病的防控提供科学依据。方法 用LWC-1型离心式空气微生物采样器采集火车站、学校、公园、广场等场所空气并分离鉴定其中的葡萄球菌,采用REP-PCR扩增不同源MRSA的基因组DNA形成聚类图谱,分析不同源MRSA的相似性。结果 气载金黄色葡萄球菌和凝固酶阴性葡萄球菌浓度沙尘天气时浓度均明显增高,与正常天气时的浓度差异有统计学意义(P<0.05);在火车站中最高,浓度分别为116.7 CFU/m³和162.0 CFU/m³。从空气中共分离得到金黄色葡萄球菌111株,其中MRSA20株;凝固酶阴性葡萄球菌179 株,其中MRCNS共11株。20株气载MRSA图谱显示菌株相似性在48%~100%之间;气载MRSA与医院临床MRSA分离株之间的相似性在50%~100%之间;与动物源MRSA之间的相似性在40%~100%之间。结论 沙尘天气空气中存在着多种葡萄球菌,而且空气中的部分MRSA株与医院临床分离株及动物源的MRSA有着较高的遗传相似性,应加强空气中葡萄球菌尤其是耐药葡萄球菌的监测及防控。

Surveillance and analysis of REP-PCR fingerprints of airborne Methicillin-resistant staphylococci in the sand and dust weather

We evaluated the diversity of airborne staphylococci in the sand and dust weather and trace the source for analysis of genetic similarities of the airborne methicillin-resistant Staphylococcus aureus (MRSA),and then provide a practical basis for preventing and controlling infectious diseases. The air samples were collected from outdoor air by LWC-1 type centrifugal sampler at railway station,university,park and square in the sand and dust weather and in the normal weather. Airborne staphylococci and MRSA were isolated and identified from the air samples. The homology of MRSA isolated from air,clinical samples and animal samples was determined by repetitive extragenic palindromic elements-PCR (REP-PCR). Median concentrations of S. aureus and coagulase-negative staphylococci aerosol were significantly increased and there was significant difference between that in the sand and dust weather and normal weather (P<0.05),and was the highest in railway station,which was 116.7 CFU/m³ and 162.0 CFU/m³,respectively. The 111 strains of S. aureus were obtained,which included 20 strains of MRSA. The 179 strains of coagulase-negative staphylococci were obtained,which included 11 strains of MRCNS. The fingerprints and the phylogenetic tree based on REP-PCR indicated that the genetic similarity index of 20 strains of MRSA was 48%-100%; airborne MRSA was 50%-100% similar to clinical strains and airborne MRSA was 40%-100% similar to animal strains. The air in the sand and dust weather was contaminated by many kinds of staphylococci aerosol and airborne MRSA expressed a closer relationship to the clinical strains and animal strains and the monitoring and prevention of airborne pathogen measures should be strengthened in the air.