耐甲氧西林金黄色葡萄球菌抗生素耐药和耐药基因的检测

Antimicrobial Susceptibility and mecA Gene Detection Study of Methicillin-resistant Staphylococcus Aureus

目的探讨北京地区社区感染和院内感染中金黄色葡萄球耐药情况变化。方法用琼脂稀释法检测了471株从北京地区收集的金黄色葡萄球菌对11种抗生素的敏感水平(其中422株菌株从1993年至2000年门诊脓疱疮患儿分离获得,49株从2000年烧伤病房住院患者分离获得)。用聚合酶链反应方法对上述菌株进行了mecA耐药基因的检测。结果引起社区感染的耐甲氧西林金黄色葡萄球菌(MRSA)的比率由1993年的12.2%上升至2000年的29.8%,对甲氧西林均表现为低度耐药。引起院内感染的金黄色葡萄球菌对甲氧西林的耐药率为63.3%,表现为高度耐药。所有的金黄色葡萄球菌对青霉素100%耐药,对红霉素、四环素、克林霉素和氯霉素的耐药率分别约80%、70%、60%和50%。引起社区感染的金黄色葡萄球菌中未发现庆大霉素和利福平耐药菌株,对环丙沙星的耐药率由1993年的2.4%上升至2000年的21.3%;引起院内感染的金黄色葡萄球菌中对庆大霉素、环丙沙星和利福平的耐药率分别为63.3%、63.3%和57.1%。所有的金黄色葡萄球菌均对夫西地酸和万古霉素敏感。2000年分离的多重耐药菌株比例较1993年有所增加。PCR对mecA耐药基因的测定结果显示,所有对甲氧西林高度耐药的金黄色葡萄球菌mecA耐药基因均呈阳性;对甲氧西林低度耐药的金黄色葡萄球菌mecA耐药基因均呈阴性。结论在本实验所及范围内,北京地区金黄色葡萄球菌的耐药率逐渐上升,mecA耐药基因测定是筛选耐药MRSA菌株的快速、简易手段。

Objective To investigate the antibiotic resistance of Staphylococcus aureus in communities and hospitals in Beijing. Methods To detect the susceptibility of 11 kinds of antibiotics of 471 strains SA isolated in Beijing with agar dilution method （422 isolates from outpatients in 1993 - 2000, 49 from burnt inpatients）, comparing the susceptibility difference of those strains. To the resistance gene of MRSA was detected with polymerase chain reaction （PCR）. Results In community-acqulred infection isolates, MRSA increased significantly from 12.2% to 29.8% during 1993 to 2000. In nosocomial infection isolates, MRSA was 63.3% in 2000, a little bit lower than that of mld-1990＇s. All the Staphylococcus aureus strains showed 100% resistance to penicillin. The resistance of SA to some non-β-1actams were： erythromycin 80%, tetracycline 70%, clindamycin 60%, chloramphenical 50%. In community-acquired infection isolates, resistance to clprofloxin increased significantly from 2.4% to 21.3% from 1993 to 2000, no isolates was found to be resistant to gentamycin, rifampin, vancomycln and fusldic acid. In nosocomial infection isolates, the resistance percentage to gentamycln, ciprofloxin and rifampin were 63.3 %, 63.3 % and 57.1% respectively. No strain was found to be resistant to vancomycln and fusidlc acid. All the MRSA strains were multl-drug resistant. MRSA strains showed higher resistance percentage to erythromycin, tetracycline, clindamycin, chloramphenical and ciprofloxin than MSSA. Detection of mecA gene by PCR showed that all the high-level methicillin-resistant strains were mecA gene positive, all the low-level methicillin-reslstant strains were mecA gene negative. Conclusion The results indicate that the resistance rate of SA in Beljing is going up. Detection of mecA gene by PCR is an easy and quick way of screening MRSA strains.