Infection prevention and control considerations in invasive group A streptococcus outbreaks

Summary: Invasive Streptococcus pyogenes (group A streptococcus, GAS) infection is associated with substantial morbidity and mortality and has shown a notable resurgence in several countries since late 2022, including the United Kingdom (UK) and Ireland. Healthcare-associated cases, particularly in maternity and acute hospital settings, present significant infection prevention and control (IPC) challenges due to the organism's high transmissibility, potential for asymptomatic carriage among patients and healthcare workers, and the rapid progression of invasive disease. Even a single healthcare-associated case may signal unrecognised transmission within the clinical environment and therefore requires prompt investigation. This IPC Toolkit article summarises practical approaches to recognising, investigating, and managing GAS outbreaks in acute healthcare settings. Current UK guidance from the UK Health Security Agency and the British Infection Association is reviewed alongside recent outbreak reports and emerging evidence relevant to hospital practice. Key operational considerations include early case recognition, structured outbreak management through an incident management team, epidemiological investigation, and microbiological characterisation of isolates, including the use of whole genome sequencing to establish transmission pathways. The article also discusses patient isolation, environmental control measures, healthcare worker screening, and the role of targeted chemoprophylaxis for high-risk contacts. Recent literature emphasises the growing role of genomic epidemiology in outbreak confirmation and highlights the operational challenges associated with healthcare worker screening and contact management. Emerging population-level data may also influence future approaches to chemoprophylaxis for contacts. This article provides a practical framework to support clinicians and IPC teams in responding effectively to suspected or confirmed healthcare-associated GAS outbreaks.