Bacteria of the streptococcus group cause many common diseases and disorder, from sore throats to meningitis. The bacteria are divided into groups A and B according to their characteristics.
Group A streptococcus (GAS) is a bacterium that can be found on people’s skin and in their throats, and often causes no sign of illness. Most GAS infections are mild and include ‘step throat’ (a common throat infection) or the skin infection impetigo. The bacteria are spread through contact with the sores or mucus of infected people. People who carry the bacteria but who have no symptoms are not usually very contagious. Washing your hands can help prevent the disease spreading.
Severe or invasive GAS disease can occur if the bacterium gets into places where it is not usually found, such as the blood, muscles or lungs. People who use steroids or have chronic illnesses are particularly vulnerable to invasive GAS disease. One of the most serious forms of invasive GAS disease is necrotizing fasciitis (also known as cellulitis), as infection that destroys muscles, fat and skin. An infected wound combined with a fever can be a sign of the disease. GAS infections can be treated with a variety of antibiotics. In the case of necrotizing fasciitis, surgery may be required to remove the affected tissue.
Group B Streptococcal disease (GBS) is the most common cause of blood infections and pneumonia, as well as meningitis in newborn babies. Most cases in babies occur in the first week of life. One in 200 babies whose mother carries GBS will develop symptoms and recover but one in 20 cases will be fatal. A woman can be tested for the disease during pregnancy by a swab of the vagina and rectum. If she tests positive, antibiotics can be given during labour. Some people carry GBS in the bowel, vagina, bladder or throat but do not become ill. Vaccines to prevent GBS are being developed.