Servicio de Microbiología Clínica, Hospital Universitario La Paz, IdiPAZ, Paseo de La Castellana, 261, Madrid 28046, Spain.
Unidad de Enfermedades Infecciosas y Microbiología Clínica. Hospital Universitario La Paz, IdiPAZ, Paseo de La Castellana, 261, Madrid 28046, Spain.
J Med Microbiol. 2013 Dec;62(Pt 12):1914-1916. doi: 10.1099/jmm.0.064683-0. Epub 2013 Sep 26.
We present a case of bacteraemia due to meticillin-resistant Staphylococcus aureus (MRSA) carrying the mecC gene. The susceptibility to meticillin of Staphylococcus aureus was investigated directly from one blood culture bottle using GenomEra MRSA/SA (Abacus Diagnostica Oy) test. This test identified S. aureus but the presence of the mecA gene result was negative, and the isolate was reported as meticillin-sensitive Staphylococcus aureus (MSSA). Susceptibility studies were done using VITEK 2 AST-P588 susceptibility cards (bioMérieux). The strain was identified as MRSA by the VITEK 2 system, although oxacillin MIC was low (0.5 µg ml(-1)). In view of these results, the isolate was tested for the presence of the mecC gene by a specific PCR and was verified as MRSA carrying mecC. The emergence of this new mecA homologue could have important consequences for the detection of MRSA when routine PCR methods are used as an identification method or provisional detection of MRSA, as in the case reported in this article, because S. aureus carrying the mecC gene will be wrongly diagnosed as meticillin susceptible. Negative results must be interpreted with caution and should be followed by conventional culture, and antimicrobial susceptibility testing or detection of mecC gene by a specific PCR.
我们报告了一例由携带 mecC 基因的耐甲氧西林金黄色葡萄球菌（MRSA）引起的菌血症。使用 GenomEra MRSA/SA（Abacus Diagnostica Oy）检测试剂盒直接从一个血培养瓶中检测金黄色葡萄球菌对甲氧西林的敏感性。该检测方法鉴定出了金黄色葡萄球菌，但 mecA 基因结果呈阴性，且该分离株被报告为耐甲氧西林金黄色葡萄球菌（MSSA）。使用 VITEK 2 AST-P588 药敏卡（bioMérieux）进行了药敏研究。VITEK 2 系统鉴定该菌株为 MRSA，尽管苯唑西林 MIC 值较低（0.5 µg ml(-1)）。鉴于这些结果，通过特异性 PCR 检测该分离株是否携带 mecC 基因，并证实其为携带 mecC 的 MRSA。当常规 PCR 方法被用作鉴定方法或如本文所述的 MRSA 的临时检测方法时，这种新的 mecA 同源物的出现可能会对 MRSA 的检测产生重要影响，因为携带 mecC 基因的金黄色葡萄球菌将被误诊为耐甲氧西林敏感。必须谨慎解读阴性结果，并应随后进行常规培养以及抗菌药物敏感性测试或通过特异性 PCR 检测 mecC 基因。
