Department of Hygiene, Sapporo Medical University School of Medicine, Sapporo, Japan.
Microb Drug Resist. 2011 Jun;17(2):241-50. doi: 10.1089/mdr.2010.0136. Epub 2011 Mar 13.
Prevalence and molecular characteristics of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) were studied in Hokkaido, the main northern island of Japan. Among the 1,015 S. aureus isolates derived from clinical specimens of outpatients collected in 2009, methicillin resistance gene mecA was detected in 189 isolates (18.6%). The most frequent staphylococcal cassette chromosome mec (SCCmec) type in MRSA was II (83.1%), followed by IV (6.9%) and V (3.2%). MRSA with type II-SCCmec showed multiple drug resistance and harbored various toxin and virulence factor genes except for Panton-Valentine leucocidin (PVL) gene. These isolates were mostly classified into sequence type 5 (ST5) (or other STs in CC5) and coagulase genotype II and were thus genetically similar to hospital-acquired MRSA, which have been predominating in Japan (New York/Japan clone). PVL gene was detected in three MRSA strains belonging to ST6 (two strains) and ST59 (one strain), having type IVa- and Vt-SCCmec, respectively, and also in two methicillin-susceptible S. aureus ST121 and ST188. The arcA gene within the arginine catabolic mobile element (ACME) was detected in the two PVL-negative ST5 MRSA strains, which had type IIa- or V-SCCmec. The PVL gene-positive ST6 and ST59 CA-MRSA strains were susceptible to more antimicrobials and had less virulence factor genes than the PVL-negative ST5 MRSA, including the ACME-arcA-positive strains. In the present study, ST6 was identified as a lineage of PVL-positive CA-MRSA, the ACME-arcA was first detected in ST5 MRSA with type V-SCCmec, and ST59 Taiwanese CA-MRSA strain was isolated in Hokkaido for the first time. These findings suggest a potential spread of these emerging CA-MRSA clones in Japan.
在日本主要的北部岛屿北海道，研究了社区获得性耐甲氧西林金黄色葡萄球菌（CA-MRSA）的流行情况和分子特征。在 2009 年从门诊患者的临床标本中分离的 1015 株金黄色葡萄球菌中，检测到 189 株（18.6%）耐甲氧西林基因 mecA。MRSA 中最常见的葡萄球菌盒式染色体 mec（SCCmec）类型是 II 型（83.1%），其次是 IV 型（6.9%）和 V 型（3.2%）。携带 II 型-SCCmec 的 MRSA 具有多种药物耐药性，并携带各种毒素和毒力因子基因，除了杀白细胞素（PVL）基因外。这些分离株主要分为 5 型（ST5）（或 CC5 中的其他 ST）和凝固酶基因型 II，因此与日本（纽约/日本克隆）占主导地位的医院获得性 MRSA 在遗传上相似。在属于 ST6（两株）和 ST59（一株）的三株 MRSA 中检测到了 PVL 基因，它们分别具有 IVa 型和 Vt 型-SCCmec，同时还在两株耐甲氧西林的金黄色葡萄球菌 ST121 和 ST188 中检测到了该基因。在两株 PVL 阴性 ST5 MRSA 中检测到了精氨酸分解移动元件（ACME）内的 arcA 基因，它们具有 IIa 型或 V 型-SCCmec。PVL 基因阳性的 ST6 和 ST59 CA-MRSA 对更多的抗菌药物敏感，并且比 PVL 阴性的 ST5 MRSA 携带更少的毒力因子基因，包括 ACME-arcA 阳性菌株。在本研究中，ST6 被确定为 PVL 阳性 CA-MRSA 的谱系，ACME-arcA 首次在具有 V 型-SCCmec 的 ST5 MRSA 中检测到，并且 ST59 台湾 CA-MRSA 株在北海道首次分离。这些发现表明这些新兴 CA-MRSA 克隆在日本有潜在的传播。
