一种简单的筛选耐甲氧西林葡萄球菌方法

A simple method to screen methicillin-resistant Staphylococcus

目的 推荐美国国家临床实验室标准化委员会 (NCCLS)关于 6 μg/ml苯唑西林 +4%NaCl盐平板 (以下简称盐平板法 )检测甲氧西林耐药葡萄球菌。方法 使用NCCLS推荐的盐平板法检测华山医院临床分离的葡萄球菌共 894株。结果 (1)耐甲氧西林金黄色葡萄球菌 (MRSA)苯唑西林纸片法的检出率为 84 .2 % (5 38/6 39) ,盐平板法的检出率为 86 .4 % (5 5 2 / 6 39) ,而耐甲氧西林凝固酶阴性葡萄球菌 (MRCNS)的检出率 2种方法分别为 82 .0 (2 0 9/ 2 5 5 )、90 .6 % (2 31/ 2 5 5 ) ;(2 )有 14株纸片法测定为中介的金黄色葡萄球菌和 2 2株纸片法检测为甲氧西林敏感 (MS)的凝固酶阴性葡萄球菌 ,盐平板检测均为甲氧西林耐药 (MR) ,经聚合酶链反应 (PCR)检测mecA基因结果均为阳性 ,显示PCR检测与盐平板检测结果一致 ;(3)随机取上述纸片法和盐平板 2种方法检测均为MS者 9株、MR者 15株 ,同时进行mecA基因的PCR检测 ,结果显示全部与盐平板法和苯唑西林纸片法检测结果符合。结论 在临床微生物实验室应该采用NCCLS推荐的 6 μg/ml苯唑西林 +4%NaCl盐平板对MRSA和MRCNS进行检测 ,以供临床诊断和选用抗生素。

Objective To recommend the National Committee for Clinical Laboratory Standards(NCCLS) method of detection of the methicillin resistance Staphylococci in clinical laboratory. Methods Using the NCCLS method of 6 μg/ml oxacillin and 4% salt agar to detect 894 Staphylococci strains isolated from clinical samples of Huashan hospital. Results (1) The positive rate of methicillin-resistant Staphylococcus aureus (MRSA) by 6 μg/ml oxacillin was 84.2% (538/639), the positive rate of MRSA by salt agar was 86.4%(552/639). The positive rates of methicillin resistant coagulase-negative Staphylococci (MRCNS) by these two methods were 82.0%(209/255) and 90.6% (231/255) respectively; (2) 14 S.aureus strains were intermedia and 22 coagulase-negative Staphylococci were methicillin sensitive (MS) detected by 6 μg/ml oxacillin, but their mecA gene was positive by PCR, the result of PCR and agar was coincidental; (3) PCR was used to detect the mecA gene of random 9 MS strains and 15 methicillin resistant (MR) strains detected by 6 μg/ml oxacillin and 4% salt agar, all of the PCR results were coincidental with the results of 6 μg/ml oxacillin and 4% salt agar. Conclusions Clincial microbiology laboratory should use the method of 6 μg/ml oxacillin and 4% salt agar recommeded by NCCLS to detect MRSA and MRCNS. It is useful for clinical diagnosis and antibiotics selection.