Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki University Hospital, Nagasaki, Japan.
Tohoku J Exp Med. 2010 Feb;220(2):165-70. doi: 10.1620/tjem.220.165.
Methicillin-resistant Staphylococcus aureus (MRSA) causes a wide range of infections in health care settings and community environments. In particular, community-acquired MRSA (CA-MRSA) is important for clinicians because many fatal cases in healthy populations have been reported. Staphylococcal cassette chromosome mec (SCCmec) is a mobile genetic element and carries the central determinant for broad-spectrum beta-lactam resistance encoded by the mecA gene. The emergence of MRSA is due to the acquisition and insertion of the SCCmec element into the chromosome. CA-MRSA is characterized as SCCmec type IV. Thus, we aimed to establish a novel multiplex real-time PCR method to distinguish SCCmec type, which enables us to evaluate the pathogenicity of MRSA. A total of 778 MRSA were isolated at Nagasaki University Hospital from 2000 to 2007. All isolates were subjected to minimal inhibitory concentration testing and PCR for SCCmec typing and detecting genes of toxins: tst (toxic shock syndrome toxin 1), sec (encoded enterotoxin type c), etb (exfoliative toxin type b), and lukS/F-PV (Panton-Valentine leukocidin). PCR was performed to amplify a total of 10 genes in the same run. The 667 MRSA clones detected from pus in 778 clones were classified as SCCmec type II (77.7%), type IV (19.2%), and type I (3.0%). 87.5% of SCCmec type II clone had tst and sec genes. No isolate was lukS/F-PV positive. The present study indicates the high rate of lukS/F-PV-negative SCCmec type IV in Nagasaki. Our PCR method is convenient for typing MRSA and detecting toxins in Japan.
耐甲氧西林金黄色葡萄球菌（MRSA）可引起医疗环境和社区环境中的各种感染。特别是，社区获得性耐甲氧西林金黄色葡萄球菌（CA-MRSA）对临床医生很重要，因为已有报道称许多健康人群中出现了致命病例。葡萄球菌盒式染色体 mec（SCCmec）是一种移动遗传元件，携带由 mecA 基因编码的广谱β-内酰胺抗性的中央决定簇。MRSA 的出现是由于 SCCmec 元件的获取和插入到染色体中。CA-MRSA 的特征是 SCCmec 类型 IV。因此，我们旨在建立一种新的多重实时 PCR 方法来区分 SCCmec 类型，这使我们能够评估 MRSA 的致病性。2000 年至 2007 年，长崎大学医院从 778 株 MRSA 中分离出 SCCmec 型。所有分离株均进行最小抑菌浓度试验和 SCCmec 型 PCR 检测毒素基因：tst（中毒性休克综合征毒素 1）、sec（编码肠毒素 C 型）、etb（剥脱毒素 B 型）和 lukS/F-PV（Panton-Valentine 白细胞毒素）。PCR 用于在同一运行中扩增总共 10 个基因。在 778 个克隆中从脓液中检测到的 667 个 MRSA 克隆被分类为 SCCmec 类型 II（77.7%）、类型 IV（19.2%）和类型 I（3.0%）。87.5%的 SCCmec 类型 II 克隆具有 tst 和 sec 基因。没有分离株为 lukS/F-PV 阳性。本研究表明长崎 SCCmec 类型 IV 的 lukS/F-PV 阴性率很高。我们的 PCR 方法方便在日本对 MRSA 进行分型和检测毒素。
