耐甲氧西林金黄色葡萄球菌检测及其耐药性研究

目的 分析耐甲氧西林的金黄色葡萄球菌（MRSA）检测方法及其耐药性。方法 采用头孢西丁、苯唑西林纸片法和PCR3种方法检测2005年安徽地区12家医院临床分离133株金黄色葡萄球菌中MRSA菌株；琼脂稀释法测定金黄色葡萄球菌对17种抗菌药物的最低抑菌浓度（MIC）。结果头孢西丁、苯唑西林纸片法及PCR法对MRSA检出率分别为52．63％、54、13％、51．87％，3种方法对MRSA检出率差异无显著性。以PCR法检出mec—A基因为判断MRSA的金标准，头孢西丁纸片法灵敏度为100％、特异度为98．44％、符合率为99、24％，r（正确诊断指数）=0．9844。苯唑西林纸片法的灵敏度为98．55％、特异度为93、75％、符合率为96．24％，r=0．923。除了青霉素-G、氨苄西林、替考拉宁、万古霉素以外，其余抗生素的耐药率，MRSA组均明显高于MSSA组（P〈0．01）。结论 头孢西丁纸片法是筛选和确认MRSA菌株的一种可靠、简便的方法；MRSA为多重耐药菌株，临床应加强检测。

Resisitance and detection of methicillin resisitant staphylococcus

Objective To evaluate three methods for detecting methicillin resistant staphylococcus aureus (MRSA) and analyze the resistance of MRSA isolated from 12 hospitals in Anhui from January to September, 2005. Method 133 strains of S.aureus isolates were tested for minimus inhibitory concentration (MIC) to 17 kinds of antimicrobial agents using agr dilution method; MRSA were detected using cefoxitin disk, oxacillin disk diffusion as well as PCR amplification for the mecA gene, respectively. Result The rates of MRSA detected by cefoxitin disk, oxacillin disk diffusion as well as PCR amplification for the mecA gene were 52.63%,54.13%,51.87% respectively. But the three groups had no significant difference (P>0.05). The specificity and sensitivity of cefoxitin disk diffusion method were higher than that of oxacillin disk diffusion method. Except penicillin-G and ampicillin, resistance rate of MRSA to other drug was higher than that of MSSA (P<0.01). Conclusion Cefoxitin disk diffusion method can be used in detecting and conforming MRSA. MRSA is resistant to multi-drugs and so detection and surveillance of them should be emphasized.