Group A streptococcal infections: guidance and data

The characteristics, diagnosis and management of group A streptococci infections.

Group A Streptococcus (GAS; Streptococcus pyogenes) is a bacterium which can colonise the throat, skin and anogenital tract. It causes a diverse range of skin, soft tissue and respiratory tract infections, including:

In rare cases, patients may go on to develop post-streptococcal complications, such as:

  • rheumatic fever
  • glomerulonephritis

GAS can occasionally cause infections that are extremely severe. Invasive GAS (iGAS) is an infection where the bacteria is isolated from a normally sterile body site, such as the blood. Any GAS manifestation can be associated with development of streptococcal toxic shock syndrome, although patients with necrotising fasciitis are at highest risk.

GAS is spread by close contact between individuals, through:

  • respiratory droplets
  • direct skin contact

It can also be transmitted environmentally, through:

  • contact with contaminated objects, such as towels or bedding
  • ingestion of food inoculated by a carrier

Invasive GAS (iGAS) infection and scarlet fever are both notifiable diseases: health professionals must inform local health protection teams of suspected cases. Guidelines are available for the public health management of iGAS cases in the community and healthcare settings and scarlet fever outbreaks in educational settings.


GAS is usually diagnosed by microbiological culture of the affected site. Serology has specific clinical uses and can be discussed with a local infection specialist.

GAS isolates from patients with healthcare-associated infections should be stored locally for a minimum of 6 months.



Previous Group A streptococcal infections: activity reports were published by Public Health England.

Published 31 July 2014
Last updated 6 April 2022 + show all updates
  1. Added Group A streptococcal infections: activity during the 2021 to 2022 season.

  2. Added link 'Invasive group A streptococcal outbreaks associated with home healthcare'.

  3. Updated link under Diagnosis to AMRHAI, which now provides diagnostic services.

  4. Added 'Group A streptococcal infections: activity during the 2018 to 2019 season' document.

  5. Latest seasonal activity document inserted into the Epidemiology subgroup (2017/2018 season)

  6. Added report on activity during the 2014 to 2015 season under epidemiology.

  7. Added 'Group A streptococcal infections: activity during the 2014 to 2015 season' to the collection.

  8. First published.