Laboratory of Medical Microbiology, Vaccine & Infectious Disease Institute, University of Antwerp, Belgium.
Belgian Reference Centre for Group A Streptococcus, Antwerp University Hospital, Antwerp, Belgium.
Genome Biol Evol. 2019 May 1;11(5):1432-1439. doi: 10.1093/gbe/evz093.
During the last two decades, there has been a public health concern of severe invasive infections caused by Group A Streptococcus (GAS) of the emm1 genotype. This study investigated the dynamics of emm1 GAS during 1994-2013 in Belgium. emm1 GAS isolated from blood, tissue, and wounds of patients with invasive infections (n = 23, S1-S23), and from patients with uncomplicated pharyngitis (n = 15, NS1-NS15) were subjected to whole-genome mapping (WGM; kpn) (Opgen). Whole-genome sequencing was performed on 25 strains (WGS; S1-S23 and NS6-NS7) (Illumina Inc.). Belgian GAS belonged to the M1T1 clone typified by the 36-kb chromosomal region encoding extracellular toxins, NAD+-glycohydrolase and streptolysin O. Strains from 1994-1999 clustered together with published strains (MGAS5005 and M1476). From 2001 onward, invasive GAS showed higher genomic divergence in the accessory genome and harbored on average 7% prophage content. Low evolutionary rate (2.49E-008; P > 0.05) was observed in this study, indicating a highly stable genome. The studied invasive and pharyngitis isolates were no genetically distinct populations based on the WGM and core genome phylogeny analyses. Two copies of the speJ superantigen were present in the 1999 and 2010 study strains (n = 3), one being chromosomal and one being truncated and associated with phage remnants. This study showed that emm1 GAS in Belgium, compared with Canada and UK M1 strains, were highly conserved by harboring a remarkable genome stability over a 19-year period with variations observed in the accessory genome.
在过去的二十年中，公众对 A 组链球菌（GAS）emm1 基因型引起的严重侵袭性感染产生了健康关注。本研究调查了 1994-2013 年期间比利时 emm1 GAS 的动态。从血液、组织和侵袭性感染患者的伤口中分离的 emm1 GAS（n=23，S1-S23），以及从无并发症咽炎患者中分离的 emm1 GAS（n=15，NS1-NS15）进行全基因组图谱分析（WGM；kpn）（Opgen）。对 25 株进行全基因组测序（WGS；S1-S23 和 NS6-NS7）（Illumina Inc.）。比利时 GAS 属于 M1T1 克隆，其特征是编码细胞外毒素、NAD+-糖水解酶和链球菌溶血素 O 的 36-kb 染色体区域。1994-1999 年的菌株与已发表的菌株（MGAS5005 和 M1476）聚集在一起。从 2001 年开始，侵袭性 GAS 在辅助基因组中显示出更高的基因组差异，平均携带 7%的噬菌体内容。在这项研究中观察到进化率较低（2.49E-008；P>0.05），表明基因组高度稳定。基于 WGM 和核心基因组系统发育分析，研究中侵袭性和咽炎分离株不是遗传上不同的群体。在 1999 年和 2010 年的研究菌株中存在两个 speJ 超抗原拷贝（n=3），一个是染色体的，一个是截短的，并与噬菌体残余物相关。本研究表明，与加拿大和英国 M1 株相比，比利时的 emm1 GAS 高度保守，在 19 年的时间里保持了显著的基因组稳定性，而辅助基因组中存在变异。
