State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, National Clinical Research Center for Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.
Department of Respiratory and Critical Care Medicine, First Hospital of Shanxi Medical University, Taiyuan, China.
Emerg Microbes Infect. 2020 Dec;9(1):2526-2535. doi: 10.1080/22221751.2020.1848354.
Previous studies have shown that livestock (LA)-MRSA ST398 evolved from a human-adapted methicillin-susceptible (MSSA) clone. However, detailed information regarding ST9 is still unclear. Here, we characterized a community-associated methicillin-resistant (CA-MRSA) ST9-SCC XII isolate that has not been previously reported to cause serious disease in China. We obtained whole-genome sequences of one ST9-t899-XII isolate-ZY462471-from a patient with bloodstream infection without livestock contact. The antibiotic susceptibilities of ZY462471 were determined and the clinical information was extracted from medical notes and compared with twenty-seven previously sequenced genomes. Phylogenetic reconstruction was performed to investigate the probable host evolutionary origins of ZY462471, and the difference in resistome and virulence factors were investigated. Virulence assay was performed to evaluate the high virulence potential of ZY462471 and compare the virulence between the closest ST9 MSSA neighbours. Clinical data suggested that ZY462471 is a CA-MRSA. Phylogenetic analysis showed a much closer relationship of ZY462471 with human-associated MSSA ST9 isolates than other LA-MRSA ST9 isolates, suggesting that ZY462471 probably evolved from ST9 MSSA predecessors by acquiring an SCC cassette. Importantly, virulence assays indicated that ZY462471 was highly virulent and compared with the MSSA ST9 predecessors, ZY462471 did not show attenuated virulence. Finally, we found that ZY462471 harboured an immune evasion cluster (IEC)-carrying βC-Φ, which is typically found in human clinical rather than LA-MRSA isolates, suggesting that ZY4762471 obtained the IEC-carrying βC-Φs from human clinical strains. Considering its high virulence potential, this strain should be monitored to prevent more widespread dissemination.
先前的研究表明，家畜（LA）-MRSA ST398 是由一种适应人类的耐甲氧西林敏感（MSSA）克隆进化而来的。然而，关于 ST9 的详细信息仍然不清楚。在这里，我们描述了一种社区获得性耐甲氧西林金黄色葡萄球菌（CA-MRSA）ST9-SCC XII 分离株，该分离株以前在中国尚未报道过引起严重疾病。我们从一名无家畜接触的血流感染患者中获得了一株 ST9-t899-XII 分离株-ZY462471 的全基因组序列。确定了 ZY462471 的抗生素药敏性，并从病历中提取了临床信息，并与 27 个已测序的基因组进行了比较。进行了系统发育重建以研究 ZY462471 的可能宿主进化起源，并研究了其耐药组和毒力因子的差异。进行了毒力测定以评估 ZY462471 的高毒力潜力，并比较了最接近的 ST9 MSSA 近邻之间的毒力。临床数据表明 ZY462471 是一种 CA-MRSA。系统发育分析表明，与其他 LA-MRSA ST9 分离株相比，ZY462471 与人类相关的 MSSA ST9 分离株的关系更为密切，这表明 ZY462471 可能是通过获得 SCC 盒从 ST9 MSSA 前身进化而来的。重要的是，毒力测定表明 ZY462471 具有高度的毒力，与 MSSA ST9 前身相比，ZY462471 的毒力并未减弱。最后，我们发现 ZY462471 携带一个免疫逃避簇（IEC）-携带βC-Φ，通常在人类临床而非 LA-MRSA 分离株中发现，这表明 ZY4762471 从人类临床株中获得了携带 IEC 的βC-Φs。考虑到其高毒力潜力，应监测该菌株以防止其更广泛传播。
