医院内气载耐甲氧西林金黄葡萄球菌（MRSA）耐药性及耐药基因分析

目的监测医院中气载耐甲氧西林金黄葡萄球菌（MRsA）对临床常用抗生素的耐药性及相关耐药基因。方法用FA-1型六级筛孔撞击式空气微生物采样器采集5所医院的大厅、ICU及病房等场所的空气，分离金黄葡萄球菌，采用头孢两丁纸片法检测MRSA，应用K-B法测定MRSA药敏情况，应用多重PCR扩增MRSA甲氧西林耐药基因rrlecA，氨基糖苷修饰酶基因aacA-aphD，大环内酯类23srRNA甲基化酶基因ermA、errnC，四环素类核糖体保护蛋白基因tetM、tetK以及金黄葡萄球菌属特异性基因16srDNA。结果共采集空气样品250份，分离气载金黄葡萄球菌219株，其中MRSA88株。所有气载MRSA均对青霉素及头孢曲松耐药，对庆大霉素、红霉素及四环素耐药率〉90％，但均对万古霉及素替考拉宁敏感。所有MRSA菌株iTIeCA基因和16srDNA基因均阳性，vat（A）、vat（B）、vat（C）基因均阴性。96％以上MRSA菌株可同时检出氨基糖苷类、红霉素类和四环素类耐药基因，呈现多重耐药；携带aacA—aphD、erm（A）或（和）erm（C）、tetM或（和）tetK耐药基因的MRSA菌株总检出率分别为96．59％、100％和96．59％。结论5所医院空气中均存在MRSA分布且呈多重耐药性，相关耐药基因检出率高。因此应加强对医院空气中致病菌的监测与消毒，预防和控制医院气源病原微生物感染的发生。

Analysis of drug resistance and drug resistance genes in airborne MRSA isolated from hospitals

Objective To monitor the phenotypes of and genes responsible for antibiotic resistance of airborne methicil- lin-resistant Staphylococcus aureus （MRSA） in hospitals. Methods Air samples were collected by FA-1 six-stage air samplers in the main lobby, ICU, and wards of five hospitals. Airborne S. aureus strains were isolated and identified from the air samples, and then the airborne MRSA strains were identified using a cefoxitin disk diffusion test. The Kirby- Bauer method was used to test the MRSA strains＂ susceptibility to antibiotics. The methieillin resistance gene mecA, ami- noglycoside resistance genes aacA and aphD, maerolide-lincosamide-streptogramin B resistance genes erm（A） and erm （C）, and tetracycline resistance genes terM and tetK were detected by multiple polymerase chain reaction. Results A total of 250 air samples were collected and 219 strains of airborne S. aureus were obtained, including 88 strains of air- borne MRSA. All airborne MRSA strains were resistant to penicillin and ceftriaxone. MRSA strains had resistance to other antibiotics of 90% and all airborne MRSA strains were sensitive to vancomycin and teicoplanin. The MecA gene and 16s rDNA gene were detected in all of the MRSA strains. The aminoglycoside resistance genes aacA and aphD, the mac- rolide-lincosamide-streptogramin B resistance gene erm（A） or erm （C）, and the tetracycline resistance gene tetM or tetK were detected in 96% or more of MRSA strains; an aminoglycoside resistance gene was detected at a rate of 96.59% o-verall, a macrolide-lincosamide streptogramin B resistance gene was detected at a rate of 100% overall, and a tetracycline resistance gene was detected at a rate of 96.59% overall. Conclusion The air in hospitals was contaminated with MR- SA, and airborne MRSA in those hospitals had developed multidrug resistance. That resistance was correlated with a high rate of detection of genes responsible for antibiotic resistance. Monitoring of airborne pathogens and disinfection must be enhanced in hospitals to prevent and control nosocomial infections.