Detroit Medical Center University Laboratories, Detroit, Michigan, USA.
Detroit Medical Center University Laboratories, Detroit, Michigan, USA
J Clin Microbiol. 2014 Nov;52(11):3928-32. doi: 10.1128/JCM.01811-14. Epub 2014 Aug 27.
Sepsis caused by Staphylococcus aureus is a major health problem worldwide. Better outcomes are achieved when rapid diagnosis and determination of methicillin susceptibility enable early optimization of antimicrobial therapy. Eight large clinical laboratories, seven from the United States and one from Scotland, evaluated the combination of the Staphylococcus QuickFISH BC and the new mecA XpressFISH assay (both AdvanDx, Woburn, MA, USA) for the detection of methicillin-resistant S. aureus in positive blood cultures. Blood cultures flagged as positive by automated blood culture instruments and demonstrating only Gram-positive cocci in clusters on Gram stain were tested by QuickFISH, a 20-min assay. If only S. aureus was detected, mecA XpressFISH testing followed. The recovered S. aureus isolates were tested by cefoxitin disk diffusion as the reference method. The QuickFISH assay results were concordant with the routine phenotypic testing methods of the testing laboratories in 1,211/1,221 (99.1%) samples and detected 488/491 S. aureus organisms (sensitivity, 99.4%; specificity, 99.6%). Approximately 60% of the samples (730) contained coagulase-negative staphylococci or nonstaphylococci as assessed by the QuickFISH assay and were not tested further. The 458 compliant samples positive exclusively for S. aureus by the QuickFISH assay were tested by the mecA XpressFISH assay, which detected 209 of 211 methicillin-resistant S. aureus organisms (sensitivity, 99.1%; specificity, 99.6%). The mecA XpressFISH assay also showed high reproducibility, with 534/540 tests performed by 6 operators over 5 days achieving reproducible results (98.9% agreement). The combination of the Staphylococcus QuickFISH BC and mecA XpressFISH assays is sensitive, specific, and reproducible for the detection of methicillin-resistant S. aureus and yields complete results in 2 h after the blood culture turns positive.
金黄色葡萄球菌引起的败血症是全球范围内的一个主要健康问题。当快速诊断和确定耐甲氧西林敏感性能够使抗菌治疗早期优化时，可以获得更好的结果。来自美国的 7 个和苏格兰的 1 个共 8 个大型临床实验室评估了 Staphylococcus QuickFISH BC 和新的 mecA XpressFISH 检测（均来自 AdvanDx，马萨诸塞州伍本）在阳性血培养物中检测耐甲氧西林金黄色葡萄球菌的组合。由自动血液培养仪器标记为阳性并仅在革兰氏染色上显示成簇革兰氏阳性球菌的血液培养物通过 QuickFISH 进行测试，这是一种 20 分钟的检测。如果仅检测到金黄色葡萄球菌，则进行 mecA XpressFISH 检测。回收的金黄色葡萄球菌分离株通过头孢西丁纸片扩散作为参考方法进行测试。QuickFISH 检测结果与 1211/1221 份（99.1%）样本中测试实验室的常规表型检测方法一致，并检测到 488/491 株金黄色葡萄球菌（敏感性为 99.4%，特异性为 99.6%）。QuickFISH 检测约 60%（730 份）的样本含有凝固酶阴性葡萄球菌或非葡萄球菌，因此未进一步检测。QuickFISH 检测仅对金黄色葡萄球菌呈阳性的 458 份符合条件的样本通过 mecA XpressFISH 检测进行了检测，该检测检测到 211 株耐甲氧西林金黄色葡萄球菌中的 209 株（敏感性为 99.1%，特异性为 99.6%）。mecA XpressFISH 检测也表现出高度的重现性，6 名操作员在 5 天内进行了 540 次测试，结果具有可重复性（98.9%的一致性）。Staphylococcus QuickFISH BC 和 mecA XpressFISH 检测组合对于检测耐甲氧西林金黄色葡萄球菌具有敏感性、特异性和可重复性，并在血液培养物转为阳性后 2 小时内提供完整结果。
