头孢西丁和苯唑西林检测耐甲氧西林金黄色葡萄球菌的比较

Comparison of Cefoxitin and Oxacillin in Detection of Meticillin-resistant Staphylococcus-aureus

目的比较头孢西丁和苯唑西林两种抗生素检测耐甲氧西林金黄色葡萄球菌(meticillin-resistant-Staphylococcus aureus,MRSA)的阳性率差异,并对91株MRSA进行临床调查,为临床诊断和控制该类菌引起感染的提供依据。方法苯唑西林及头孢西丁分别采用K-B法和MIC法鉴定213株金黄色葡萄球菌中的MRSA阳性率。结果213株金黄色葡萄球菌中对苯唑西林耐药的有99株(46.5%);用头孢西丁纸片法和MIC法检测结果一致,耐药菌株有91株(42.7%);以头孢西丁检测方法作为标准,苯唑西林检测方法的假阳性率为8.1%,假阴性率为0%;MRSA的高发病区为重症监护病房(ICU)和呼吸科;MRSA对10种抗生素的耐药率高于MSSA。结论检测MRSA头孢西丁法优于苯唑西林法;MRSA具有多重耐药的特性,应严格控制MRSA医院感染。

OBJECTIVE We explored the difference of positive rate of oxacillin and cefoxitin in detection of MRSA to evaluate infection and drug resistance status of MRSA populations. METHODS Totally 213 clinical isolates of Staphylococcus aureus （SA） were collected. Every one was tested by three ways, there were routine oxacillin disk diffusion tests, cefoxitin disk diffusion tests （cefoxitin 30 ~g） and cefoxitin minimal inhibitory concentrations （MIC）. RESULTS The positive rate of oxacillin disk diffusion tests was 46.5%, and the positive rate of cefoxitin disk diffusion tests was 42.7% and the MIC of cefoxitin for SA confirmed the result of cefoxitin disk diffusion tests. We regarded cefoxitin disk diffusion tests as criteria, then, the false positive rate and false negative rate of oxacillin disk diffusion tests were 8. 1% and 0%. From the data of antimicrobial susceptibility we got the conclusion that the MRSA showed higher drug resistance than MSSA. Most MRSA came from ICU and respiratory unit, and its drug resistance was higher than MSSA （P〈0.05）. CONCLUSIONS For test of MRSA oxacillin is better than cefoxitin. MRSA is resistant to different antibiotics,so we should pay great heed to its effective control.