Graduate Institute of Medical Science, National Defense Medical Center and Tri-Service General Hospital, Taipei, Taiwan, Republic of China.
PLoS One. 2012;7(1):e30394. doi: 10.1371/journal.pone.0030394. Epub 2012 Jan 23.
Staphylococcus aureus causes a variety of severe infections such as bacteremia and sepsis. At present, 60-80% of S. aureus isolates from Taiwan are methicillin resistant (MRSA). It has been shown that certain MRSA clones circulate worldwide. The goals of this study were to identify MRSA clones in Taiwan and to correlate the molecular types of isolates with their phenotypes.
A total of 157 MRSA isolates from bacteremic patients were collected from nine medical centers. They were typed based on polymorphisms in agr, SCCmec, MLST, spa, and dru. Phenotypes characterized included Panton-Valentine leucocidin (pvl), inducible macrolide-lincosamide-streptogramin B resistance (MLSBi), vancomycin (VA) and daptomycin (DAP) minimal inhibitory concentrations (MIC), and superantigenic toxin gene profiles. Difference between two consecutive samples was determined by Mann-Whitney-U test, and difference between two categorical variables was determined by Fisher's exact test.
Four major MRSA clone complexes CC1, CC5, CC8, and CC59 were found, including 4 CC1, 9 CC5, 111 CC8, and 28 CC59 isolates. These clones had the following molecular types: CC1: SCCmecIV and ST573; CC5: SCCmecII and ST5; CC8: SCCmecIII, ST239, and ST241, and CC59: SCCmecIV, SCCmecV(T), ST59, and ST338. The toxin gene profiles of these clones were CC1: sec-seg-(sei)-sell-selm-(seln)-selo; CC5: sec-seg-sei-sell-selm-(seln)-selp-tst1; CC8: sea-selk-selq, and CC59: seb-selk-selq. Most isolates with SCCmecV(T), ST59, spat437, and dru11 types were pvl(+) (13 isolates), while multidrug resistance (≥4 antimicrobials) were associated with SCCmecIII, ST239, spa t037, agrI, and dru14 (119 isolates) (p<0.001). One hundred and twenty four isolates with the following molecular types had higher VA MIC: SCCmecII and SCCmecIII; ST5, ST239, and ST241; spa t002, t037, and t421; dru4, dru10, dru12, dru13, and dru14 (p<0.05). No particular molecular types were found to be associated with MLSBi phenotype.
Four major MRSA clone complexes were found in Taiwan. Further studies are needed to delineate the evolution of MRSA isolates.
金黄色葡萄球菌可引起多种严重感染，如菌血症和败血症。目前，台湾 60-80%的金黄色葡萄球菌分离株对甲氧西林耐药（MRSA）。已经表明，某些 MRSA 克隆在全球范围内传播。本研究的目的是鉴定台湾的 MRSA 克隆，并将分离株的分子类型与表型相关联。
从 9 家医疗中心采集了 157 株菌血症患者的 MRSA 分离株。根据 agr、SCCmec、MLST、spa 和 dru 的多态性对其进行分型。表型特征包括杀白细胞素 Panton-Valentine (pvl)、诱导性大环内酯-林可酰胺-链阳菌素 B 耐药性（MLSBi）、万古霉素 (VA) 和达托霉素 (DAP) 最小抑菌浓度 (MIC) 以及超抗原毒素基因谱。连续两个样本之间的差异通过 Mann-Whitney-U 检验确定，两个分类变量之间的差异通过 Fisher's 确切检验确定。
发现了 4 种主要的 MRSA 克隆复合体 CC1、CC5、CC8 和 CC59，包括 4 株 CC1、9 株 CC5、111 株 CC8 和 28 株 CC59 分离株。这些克隆具有以下分子类型：CC1：SCCmecIV 和 ST573；CC5：SCCmecII 和 ST5；CC8：SCCmecIII、ST239 和 ST241，以及 CC59：SCCmecIV、SCCmecV(T)、ST59 和 ST338。这些克隆的毒素基因谱为 CC1：sec-seg-(sei)-sell-selm-(seln)-selo；CC5：sec-seg-sei-sell-selm-(seln)-selp-tst1；CC8：sea-selk-selq，以及 CC59：seb-selk-selq。大多数携带 SCCmecV(T)、ST59、spat437 和 dru11 型的分离株为 pvl(+)（13 株），而多药耐药性（≥4 种抗生素）与 SCCmecIII、ST239、spa t037、agrI 和 dru14 相关（119 株）（p<0.001）。具有以下分子类型的 124 株分离株的 VA MIC 更高：SCCmecII 和 SCCmecIII；ST5、ST239 和 ST241；spa t002、t037 和 t421；dru4、dru10、dru12、dru13 和 dru14（p<0.05）。未发现特定的分子类型与 MLSBi 表型相关。
在台湾发现了 4 种主要的 MRSA 克隆复合体。需要进一步研究来描绘 MRSA 分离株的进化。
