Chalker Victoria J, Smith Alyson, Al-Shahib Ali, Botchway Stella, Macdonald Emily, Daniel Roger, Phillips Sarah, Platt Steven, Doumith Michel, Tewolde Rediat, Coelho Juliana, Jolley Keith A, Underwood Anthony, McCarthy Noel D
Emerg Infect Dis. 2016 Jun;22(6):973-80. doi: 10.3201/eid2206.142050.
Single-strain outbreaks of Streptococcus pyogenes infections are common and often go undetected. In 2013, two clusters of invasive group A Streptococcus (iGAS) infection were identified in independent but closely located care homes in Oxfordshire, United Kingdom. Investigation included visits to each home, chart review, staff survey, microbiologic sampling, and genome sequencing. S. pyogenes emm type 1.0, the most common circulating type nationally, was identified from all cases yielding GAS isolates. A tailored whole-genome reference population comprising epidemiologically relevant contemporaneous isolates and published isolates was assembled. Data were analyzed independently using whole-genome multilocus sequencing and single-nucleotide polymorphism analyses. Six isolates from staff and residents of the homes formed a single cluster that was separated from the reference population by both analytical approaches. No further cases occurred after mass chemoprophylaxis and enhanced infection control. Our findings demonstrate the ability of 2 independent analytical approaches to enable robust conclusions from nonstandardized whole-genome analysis to support public health practice.
化脓性链球菌感染的单菌株暴发很常见，且往往未被发现。2013年，在英国牛津郡独立但位置相邻的养老院中，发现了两起侵袭性A组链球菌（iGAS）感染聚集性病例。调查包括走访每家养老院、查阅病历、员工调查、微生物采样和基因组测序。从所有分离出A组链球菌的病例中，均鉴定出化脓性链球菌emm 1.0型，这是全国最常见的流行型别。构建了一个定制的全基因组参考群体，其中包括具有流行病学相关性的同期分离株和已发表的分离株。使用全基因组多位点测序和单核苷酸多态性分析对数据进行独立分析。来自养老院工作人员和居民的6株分离株形成了一个单一聚类，两种分析方法均表明该聚类与参考群体不同。在进行大规模化学预防和加强感染控制后，未再出现其他病例。我们的研究结果表明，两种独立的分析方法能够从非标准化的全基因组分析中得出可靠结论，以支持公共卫生实践。
