Department of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan.
Division of Endocrinology and Metabolism, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
Int J Antimicrob Agents. 2020 Aug;56(2):106047. doi: 10.1016/j.ijantimicag.2020.106047. Epub 2020 Jun 13.
Clonal complex 59 (CC59) is the dominant community-associated methicillin-resistant Staphylococcus aureus (MRSA) strain in Taiwan and includes the Asian-Pacific clone with Panton-Valentine leukocidin (PVL)-negative/staphylococcal cassette chromosome mec (SCCmec) IVg and the Taiwan clone characterised as PVL-positive/SCCmec V (5C2&5). Nevertheless, data on the evolutionary history of the two dominant CC59 MRSA clones in Taiwan are scarce. In this study, a total of 258 CC59 S. aureus strains from Taiwan were classified by multiple-locus variable-number tandem repeat analysis (MLVA), which revealed two major clusters (MT1 and MT2) with distinct mobile genetic elements (MGEs). However, sequencing and PCR mapping of the β-lactamase-producing plasmid revealed no difference among all CC59 S. aureus strains. Bayesian evolutionary analysis of 18 of the CC59 S. aureus strains based on core genome alignment revealed two clades: (i) Clade A, which shared the samples with MT1, had the features of mainly harbouring gentamicin-resistant MES or MES, φSA3 translocation in νSaβ and SCCmec IVg; and (ii) Clade B, which shared the samples with MT2, had the features of mainly harbouring streptomycin-resistant MES, PVL phage and SCCmec V (5C2&5). Based on the time-calibrated phylogenetic tree, the estimated time of divergence of the two clades was in the 1980s. These results suggest that the CC59 S. aureus progenitor acquired a β-lactamase-producing plasmid and then developed the varied genetic backgrounds, which were associated with the acquisition and maintenance of distinct MGEs, leading to differences in antimicrobial susceptibility profiles and molecular virulence determinants.
克隆复合体 59（CC59）是台湾地区主要的社区相关耐甲氧西林金黄色葡萄球菌（MRSA）菌株，包括无杀白细胞素（PVL）/阴性葡萄球菌盒染色体 mec（SCCmec）IVg 的亚太克隆和特征为 PVL 阳性/SCCmec V（5C2&5）的台湾克隆。然而，关于台湾地区这两个主要 CC59 MRSA 克隆的进化历史的数据很少。在这项研究中，通过多位点可变数目串联重复分析（MLVA）对来自台湾的 258 株 CC59 金黄色葡萄球菌进行了分类，结果显示存在两个主要聚类（MT1 和 MT2），具有不同的移动遗传元件（MGEs）。然而，对所有 CC59 金黄色葡萄球菌菌株的β-内酰胺酶产生质粒进行测序和 PCR 图谱分析显示，所有菌株之间没有差异。基于核心基因组比对，对 18 株 CC59 金黄色葡萄球菌菌株进行贝叶斯进化分析，结果显示存在两个分支：（i）分支 A 与 MT1 共享样本，其特征主要是携带庆大霉素耐药的 MES 或 MES、φSA3 在 νSaβ 中的转位和 SCCmec IVg；（ii）分支 B 与 MT2 共享样本，其特征主要是携带链霉素耐药的 MES、PVL 噬菌体和 SCCmec V（5C2&5）。基于时间校准的系统发育树，估计这两个分支的分歧时间在 20 世纪 80 年代。这些结果表明，CC59 金黄色葡萄球菌的祖先获得了一个产生β-内酰胺酶的质粒，然后发展出不同的遗传背景，这与不同的 MGEs 的获得和维持有关，导致了抗菌药物敏感性谱和分子毒力决定因素的差异。
