Control of an outbreak of invasive Group A Streptococcus in a care home in Lincolnshire, England

Abstract

In March 2024, the East Midlands Health Protection Team was notified of a case of invasive Group A Streptococcus (iGAS) infection in an elderly care home resident. Twenty-two days later, another case in a resident from the same floor of the care home was notified. In accordance with national guidelines, an outbreak was declared, and a multidisciplinary outbreak control team (OCT) was urgently convened. Screening for GAS throat carriage was undertaken for staff and residents, excluding those receiving end-of-life care. All isolates were strain typed and characterised. Infection prevention and control (IPC) visits were undertaken to provide ongoing support. Screening identified five residents and five staff members positive for GAS. Antibiotic prophylaxis was provided to all staff throughout the setting (n = 74) and all residents on the affected floor (n = 35). Three individuals were positive on repeat screening. All staff and residents screened negative after 4 months and the two clinical cases recovered. Eleven of the 12 GAS isolates were identified as emm 3.93. This outbreak highlighted the importance of rapid screening, possible only through the deployment of a dedicated team, and rescreening post-decolonising treatment, as a means to contain such outbreaks.

Keywords: care home; iGAS; infectious disease; outbreak; public health.

Figure 1.

Distribution according to timing of symptom onset of confirmed invasive Group A Streptococcus cases (n = 2) and Group A Streptococcus cases identified from screening samples (n = 10) linked to an outbreak in a care home, Lincolnshire.

Figure 2.

Phylogenetic tree of emm 3.93 outbreak isolates. The tree is made up of 202 different Streptococcus pyogenes emm 3.93 isolates, 189 contemporary, 13 from the investigation (two iGAS isolates, nine isolates via screening, two isolates via clearance screening). The investigation isolates are two SNPs from the nearest contemporary isolates. 567 variant positions that were non-recombinatoric as identified by Gubbins (Version 2.3.4) were used in its construction [8]. The figure was generated via iTOIL [9].