Sun Lu, Wu Dandan, Chen Yan, Wang Qian, Wang Haiping, Yu Yunsong
Department of Infectious Diseases, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Department of Infectious Diseases, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Int J Med Microbiol. 2017 Sep;307(6):346-352. doi: 10.1016/j.ijmm.2017.07.002. Epub 2017 Jul 13.
Sequence type 88 community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) strain SR434, isolated from an outpatient with skin and soft tissue infection, was subjected to whole genome sequencing, antimicrobial susceptibility testing, mouse skin infection model and hemolysis analysis to identify its virulence and resistance determinants. MRSA strain SR434 is resistant to clindamycin, erythromycin and fosfomycin. Four plasmids with resistance genes were identified in this strain, including a 20,658bp blaZ-carrying plasmid, a 2473bp ermC-carrying plasmid, a 2622bp fosB7-carrying plasmid (86% identity with plasmid in a ST2590 MRSA strain) and a 4817bp lnuA-carrying plasmid (99% identity with pLNU4 from bovine coagulase-nagetive Staphylococci). This strain contains staphylococcal cassette chromosome mec type IV and does not contain arginine catabolic mobile element or Panton-Valentine-Leukocidin. SR434 harbors genomic islands νSaα, νSaβ, νSaγ and ΦSa3 and pathogenicity islands νSa2 that carries genes encoding toxic shock syndrome toxin 1, superantigen enterotoxin C and superantigen enterotoxin L. Mouse skin infection model results show that SR434 had similar virulence potential causing invasive skin infection as a PVL-negative epidemic Korea clone HL1 (ST72). CA-MRSA strain of ST88 lineage might be a great concern for its high virulence. PVL has limited contribution to virulence phenotype among this lineage.
从一名患有皮肤和软组织感染的门诊患者中分离出的序列类型88社区获得性耐甲氧西林金黄色葡萄球菌（CA-MRSA）菌株SR434，进行了全基因组测序、抗菌药敏试验、小鼠皮肤感染模型和溶血分析，以确定其毒力和耐药决定因素。MRSA菌株SR434对克林霉素、红霉素和磷霉素耐药。在该菌株中鉴定出四个带有耐药基因的质粒，包括一个携带blaZ的20,658bp质粒、一个携带ermC的2473bp质粒、一个携带fosB7的2622bp质粒（与ST2590 MRSA菌株中的质粒有86%的同一性）和一个携带lnuA的4817bp质粒（与来自牛凝固酶阴性葡萄球菌的pLNU4有99%的同一性）。该菌株含有IV型葡萄球菌盒式染色体mec，不含有精氨酸分解代谢移动元件或杀白细胞素。SR434含有基因组岛νSaα、νSaβ、νSaγ和ΦSa3以及致病岛νSa2，后者携带编码中毒性休克综合征毒素1、超抗原肠毒素C和超抗原肠毒素L的基因。小鼠皮肤感染模型结果显示，SR434引起侵袭性皮肤感染的毒力潜力与PVL阴性的流行韩国克隆HL1（ST72）相似。ST88谱系的CA-MRSA菌株因其高毒力可能令人高度关注。在这一谱系中，PVL对毒力表型的贡献有限。
