Streptococcal infections


Streptococcal infections are caused by the streptococcus group of bacteria and can infect any age group. The most common are Group A and Group B streptococcal infections. Antibiotic treatment usually is the standard treatment of choice.

Group A streptococcal infections

Group A streptococcus (GAS)is a streptococcus pyogenes 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 (STSS), although patients with necrotising fasciitis are at highest risk.

GAS is spread by close contact between individuals, through respiratory droplets and direct skin contact.

It can also be transmitted environmentally, through contact with contaminated objects, such as towels or bedding or ingestion of food inoculated by a carrier.

GAS is usually diagnosed by microbiological culture of the affected site.

Since January 2010, scarlet fever is no longer a notifiable disease in Scotland. Laboratory confirmed reports of GAS from upper respiratory samples are used as a proxy for scarlet fever.

iGAS are also reported to our organisation through an enhanced questionnaire and isolates are sent to reference laboratory for further emm typing.


Further guidance on GAS infections can be found on the Public Health England (PHE) website.

For all infection prevention and control guidance visit the A-Z ​pathogens section of the National Infection and Prevention Control Manual.

Data and surveillance

GAS infections generally have a seasonal pattern of illness with peaks usually seen during the winter and spring months. For the 2017 to 2018 season, there was an increase in laboratory confirmed GAS, scarlet fever and iGAS infections across Scotland. This increase was greater than the previous two seasons of 2015 to 2016 and 2016 to 2017, but was similar to that seen in 2014 to 2015.