Streptococcus pyogenes infection may have serious outcomes for patients, particularly for the elderly. Clusters linked to community healthcare are increasingly being detected, often protracted and point source identification challenging. Such clusters accounted for 71 (31%) of 228 total clusters (with one iGAS plus one or more iGAS/GAS linked cases) notified to the reference laboratory in England between 2018-2021. Despite additional IPC for COVID-19, 15 and 18 clusters in elderly care have been detected in 20/21, respectively. Surveillance data for iGAS indicates that the five most common emm types in England in 2018-21 were emm 1, 108, 89, 66, and 12, and were responsible for 34 of the 71 (48%) of iGAS/GAS clusters in elderly care. Other, less common types identified included emm 44, 28, 87 and 94.
Single nucleotide polymorphism (SNP) analyses were performed from WGS data for seven of the clusters (emm 1.0 (n=2); emm 89.0 (n=2), emm 28.0; emm 44.0; emm 94.0). Six of the seven clusters had links to healthcare delivered both at home and in nursing/care home, and one cluster in two care homes that were under the same management. WGS data from epidemiologically linked cases clustered more closely (0-14SNP) than their counterpart sporadic strains (29-90 SNP). Two cases were excluded from a large and protracted cluster in the community with iGAS/GAS emm 44.0 isolates. The management of these clusters was impacted by the WGS cluster analysis, and an enhanced centralised reference laboratory activity is therefore warranted and will be key to improving detection and recognition of clusters in the community and prompt public health interventions.