Carrying group B Streptococcus (GBS) is perfectly normal and natural whether you are or you are not pregnant.

GBS colonisation

GBS is a normal bacterium which colonises (lives in or on without harming) up to 30% of adults in the UK, usually without symptoms or side-effects. It is most commonly found in the intestines, as part of the normal gut flora (bacteria living in the gastrointestinal tract). It is also often found in the vagina of adult women.

A positive vaginal or rectal swab result for GBS means a woman is colonised with or carries GBS at the time the swab was taken – not that she is ill. (However, if GBS is found in the urine, this is usually GBS infection – urine is normally sterile – and GBS urine infections should be treated at the time of diagnosis with oral antibiotics and the treatment repeated if necessary until urine tests come back clear. Click here for more information.)

GBS infection

GBS can, however, occasionally cause infection, most commonly in newborn babies and more rarely in adults. GBS infection is diagnosed when the bacteria are grown from body fluids that are usually sterile, such as blood or spinal fluid. These are known as cultures and normally take one to two days to complete.

When GBS infection occurs in adults, it usually (though not always) does so in those with serious underlying medical conditions (such as diabetes mellitus, cancer or liver disease) which reduce the effectiveness of the immune system; the elderly; and pregnant women. And, although uncommon, GBS infection in adults displays a whole spectrum of severity, from easily treated to very serious, particularly in non-pregnant adults.

The overall rate of GBS infection per 100,000 population for 2014 was 2.8 per 100,000 population for England, Wales and Northern Ireland combined (source: PHE). GBS infections in adults are usually skin and soft tissue infections (such as infection of skin ulcers caused by poor circulation and diabetes, or pressure sores in patients confined to bed), blood infection (sepsis), pneumonia and urinary tract infections (such as kidney, bladder or prostate infections). GBS may also cause meningitis in adults as well as bone infections (osteomyelitis) and deep eye infections (endophthalmitis).

Early recognition and treatment is important for the successful treatment of GBS infection in adults. High doses of antibiotics such as penicillin should be administered and therapy should not be stopped prematurely. In some cases, surgery may be necessary to drain infected sites and remove damaged tissue. GBS infections, especially the more deep-seated ones, require expert care, prolonged courses of antibiotics and sometimes more than one antibiotic at the same time. Due to the varied nature of these infections, it is impossible to generalise about what is the most appropriate treatment.

Most GBS infection can be treated successfully, although some people will require all the expertise of intensive care facilities. Not all hospitals have such a facility and so some ill patients will have to be transferred to one with these specialised facilities.