Microbiology Division, Institute of Biological Science, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia.
Jpn J Infect Dis. 2012;65(6):502-9. doi: 10.7883/yoken.65.502.
Staphylococcus aureus is a persistent human pathogen responsible for a variety of infections ranging from soft-tissue infections to bacteremia. The objective of this study was to determine genetic relatedness between methicillin-resistant S. aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) strains. We isolated 35 MRSA and 21 MSSA strains from sporadic cases at the main tertiary hospital in Terengganu, Malaysia, screening them for the presence of virulence genes. Their genetic relatedness was determined by accessory gene regulator (agr) types, PCR-restriction fragment length polymorphism (RFLP) of the coa gene, pulsed-field gel electrophoresis (PFGE), S. aureus protein A (spa), and multilocus-sequence typing (MLST). We found that 57% of MRSA and 43% of MSSA strains harbored enterotoxin genes. The majority (87.5%) of the strains were agr type I. PCR-RFLP and PFGE genotyping of the coa gene revealed that MRSA strains were genetically related, whereas MSSA strains had higher heterogeneity. The combined genotype, MLST-spa type ST239-t037, was shared among MRSA and MSSA strains, indicating that MRSA strains could have evolved from MSSA strains. Two combined MLST-spa types were present in MRSA strains, whereas 7 different MLST-spa types were detected in MSSA strains, including 2 combined types (ST779-t878 and ST1179-t267) that have not been reported in Malaysia. In conclusion, enterotoxin genes were more prevalent in MRSA than in MSSA strains in the Terengganu hospital. The MSSA strains were genetically more diverse than the MRSA strains.
金黄色葡萄球菌是一种持久的人类病原体，可导致各种感染，从软组织感染到菌血症。本研究的目的是确定耐甲氧西林金黄色葡萄球菌（MRSA）和甲氧西林敏感金黄色葡萄球菌（MSSA）菌株之间的遗传相关性。我们从马来西亚登嘉楼州主要的三级医院的散发病例中分离出 35 株 MRSA 和 21 株 MSSA 菌株，筛选它们是否存在毒力基因。通过辅助基因调节（agr）型、coa 基因 PCR-限制性片段长度多态性（RFLP）、脉冲场凝胶电泳（PFGE）、金黄色葡萄球菌蛋白 A（spa）和多位点序列分型（MLST）确定它们的遗传相关性。我们发现 57%的 MRSA 和 43%的 MSSA 菌株携带肠毒素基因。大多数（87.5%）菌株为 agr 型 I。coa 基因 PCR-RFLP 和 PFGE 基因分型显示 MRSA 菌株具有遗传相关性，而 MSSA 菌株具有更高的异质性。MRSA 和 MSSA 菌株均存在共同基因型 MLST-spa 型 ST239-t037，表明 MRSA 菌株可能是由 MSSA 菌株进化而来。两种共同的 MLST-spa 类型存在于 MRSA 菌株中，而 7 种不同的 MLST-spa 类型存在于 MSSA 菌株中，包括在马来西亚尚未报道的 2 种共同类型（ST779-t878 和 ST1179-t267）。总之，登嘉楼医院的 MRSA 菌株比 MSSA 菌株更普遍携带肠毒素基因。MSSA 菌株的遗传多样性比 MRSA 菌株更大。
