Yamazumi T, Furuta I, Diekema D J, Pfaller M A, Jones R N
Medical Microbiology Division, Department of Pathology University of Iowa College of Medicine, Iowa City, Iowa, USA.
J Clin Microbiol. 2001 Oct;39(10):3633-6. doi: 10.1128/JCM.39.10.3633-3636.2001.
The Vitek automated susceptibility testing system with a modified gram-positive susceptibility (GPS) 106 card (bioMerieux Vitek, Inc., Hazelwood. Mo.) and a rapid slide latex agglutination test (MRSA-Screen test; Denka Seiken Co., Ltd., Tokyo, Japan) were evaluated for their abilities to detect oxacillin resistance in coagulase-negative staphylococci (CoNS). The reference broth microdilution method and the detection of the mecA gene by PCR ("gold standard" reference result) were used to compare the results obtained with the commercial products. A total of 123 clinical isolates consisting of eight species were selected from U.S. surveillance collections. Among the mecA-positive isolates (95 strains), 30 isolates were initially negative on the MRSA-Screen test read at 3 min. When the agglutination reaction was extended for 10 min, 26 of the 30 isolates became positive. For a different four isolates, the oxacillin MIC was < or =0.25 microg/ml on the Vitek GPS 106 card. Among the mecA-negative isolates (28 strains), for two Staphylococcus warneri, two S. lugdunensis, and two S. saprophyticus strains MICs were > or =0.5 microg/ml by the reference broth microdilution method. Four of these isolates were also categorized as resistant with the Vitek GPS 106 card and two isolates were positive by the MRSA-Screen test. Overall, the MRSA-Screen test, GPS 106 card, and reference broth microdilution method had sensitivities of 95.7 (result at 10 min), 95.7, and 100%, respectively, and specificities of 92.8, 85.7, and 78.5%, respectively. Although the MRSA-Screen test required a slight procedural modification, both commercial methods achieved a sensitivity and specificity at detecting oxacillin resistance in CoNS at a level that was acceptable for clinical laboratory use.
采用配备改良革兰氏阳性药敏（GPS）106卡片的Vitek自动药敏检测系统（生物梅里埃公司，密苏里州黑兹尔伍德）和快速玻片乳胶凝集试验（MRSA-Screen试验；日本东京电和化成工业株式会社），评估其检测凝固酶阴性葡萄球菌（CoNS）对苯唑西林耐药性的能力。采用参考肉汤微量稀释法和通过聚合酶链反应检测mecA基因（“金标准”参考结果）来比较这两种商业产品的检测结果。从美国监测样本中选取了总共123株由8个菌种组成的临床分离株。在mecA阳性分离株（95株）中，有30株在MRSA-Screen试验3分钟读数时最初为阴性。当凝集反应延长至10分钟时，30株中的26株变为阳性。对于另外4株分离株，Vitek GPS 106卡片上苯唑西林的最低抑菌浓度（MIC）≤0.25微克/毫升。在mecA阴性分离株（28株）中，通过参考肉汤微量稀释法，两株华纳葡萄球菌、两株路邓葡萄球菌和两株腐生葡萄球菌的MIC≥0.5微克/毫升。这些分离株中有4株在Vitek GPS 106卡片上也被归类为耐药，两株在MRSA-Screen试验中呈阳性。总体而言，MRSA-Screen试验、GPS 106卡片和参考肉汤微量稀释法的敏感性分别为95.7%（10分钟结果）、95.7%和100%，特异性分别为92.8%、85.7%和78.5%。虽然MRSA-Screen试验需要对操作程序稍作修改，但这两种商业方法在检测CoNS对苯唑西林耐药性方面的敏感性和特异性达到了临床实验室可接受的水平。
