An outbreak of an uncommon emm type (emm66.0) of group A streptococcus (GAS) occurred in England and Wales between January 2016 and May 2017, involving 52 individuals who were homeless or injecting drugs users. In order to investigate the outbreak, epidemiological and network analysis were performed; moreover 55 isolates (32 outbreak, 5 non-outbreak and 13 historical - 2005-2015) were tested with whole genome sequencing (WGS), antimicrobial resistance determination, Bayesian evolutionary analysis (BEAST). Forty one isolates (including 32 outbreak strains) belonged to a single emm66.0 clade (average SNP difference 6.6; range 0-16 SNPs) separate from the other isolates and two strains previously considered part of the outbreak (SNP average: 5876; range 93-8417 SNPs). Antibiotic resistance was not detected in the outbreak clone. No common source of infection was identified. WGS confirmed expansion of an emm66.0 clone in a hard-to-reach population and enabled refinement of the initial case definition.

中文翻译：

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2016年1月至2017年5月，英格兰和威尔士的全国注射mm66群A链球菌（GAS）暴发的人群进行基因组测序。

在2016年1月至2017年5月之间，英格兰和威尔士爆发了A群链球菌（GAS）罕见的mm2型（emm66.0）暴发，涉及52名无家可归者或注射吸毒者。为了调查疫情，进行了流行病学和网络分析。此外，通过全基因组测序（WGS），抗菌素耐药性测定，贝叶斯进化分析（BEAST）对55个分离株（32个暴发，5个非暴发和13个历史暴发-2005-2015）进行了测试。41个分离株（包括32个暴发菌株）属于一个emm66.0进化枝（平均SNP差异6.6；范围0-16 SNP），与其他分离株和之前被认为是暴发一部分的两个菌株（SNP平均值：5876；范围） 93-8417 SNP）。在爆发克隆中未检测到抗生素耐药性。没有发现常见的感染源。WGS证实了emm66.0克隆在难以到达的人群中的扩展，并能够完善初始病例的定义。