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:
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:
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.