头孢西丁替代苯唑西林检测"耐甲氧西林"的金黄色葡萄球菌和凝固酶阴性葡萄球菌

目的探讨头孢西丁纸片扩散法替代苯唑西林检测耐甲氧西林金黄色葡萄球菌和凝固酶阴性葡萄球菌(MRCNS)的准确率。方法临床标本培养鉴定出的金黄色葡萄球菌和凝固酶阴性的葡萄球菌同时用苯唑西林和头孢西丁筛选(K-B法)耐药菌株,再用PBP2a胶乳法进一步检测耐药菌株的mecA基因。结果121株的葡萄球菌,对苯唑西林的耐药率为97.5%,其中金黄色葡萄球菌31株,表皮葡萄球菌67株,腐生葡萄球菌18株,溶血葡萄球菌5株,用PBP2a胶乳试剂和头孢西丁纸片检测金葡菌中MRSA发生率均为77.4%(24/31),凝固酶阴性葡萄球菌中MRCNS发生率96.6%(87/90)和94.4%(85/90)。头孢西丁纸片扩散法的符合率为99%(109/111)。结论苯唑西林纸片扩散法检测MRSA假阳性率较高,而头孢西丁纸片法(K-B法)与PBP2a胶乳凝集法检测MRSA和MRCNS的结果相近,适合实验室推广使用。

Replacing Oxacillin by Cefoxitin for Detection of MRSA and MRCNS with K-B Method

Objective To investigate the detection of Methicillin-resistant Staphylococcus aureus(MRSA) and Methicillin Resistant Coagulase-Negative Staphylococci(MRCNS) with K-B method in which Oxacillin was replaced by Cefoxitin,and evaluate it's accuracy.Methods MRSA and MRCNS were selected from staphylococci by Oxacillin and Cefoxitin respectively,and mec-A gene was detected by PBP2a latex agglutination method in drug-resistant strain.Results Among 121 strains of stapylococcus,31 strains were S.aureus,67 strains were S.epidermidis,18 strains were S.saprophyticus and 5 strains were Staphylococcus simulans,97.5 percent of them was resistant to oxacilline.Among 31 stains of S.aureus,Both of PBP2a latex agglutination method and Cefoxitin KB method had the same results,77.4 percent of S.aureus(24/31) was confirmed as MRSA.96.6%(87/90) and 94.4%(85/90) of Coagulase-Negative Staphylococci was identified as MRCNS with PBP2a latex agglutination and Cefoxitin K-B method respectively.Conclusions Oxacillin(K-B) method has the higher false positive rate for detecting MRSA,the result of Cefoxitin(K-B) method is similar to PBP2a latex agglutination for identifying MRSA and MRCNS,so it is suitable for clinical laboratory.