Group B Streptococcal Infection in Newborns
Dr Kathryn Johnson, Consultant in Neonatal Medicine & Honorary Senior Lecturer
Group B Streptococcus (GBS) or to give it it’s official term, Streptococcus agalactiae, is a Gram positive diplococcus found commonly colonising the gastrointestinal or genital tract.
Being colonised with GBS is not in itself a problem and in pregnant women is generally asymptomatic. However, colonisation during pregnancy is the major risk factor for the development of potentially devastating GBS infection in the newborn baby.
Why is it important in clinical negligence?
I have been involved in several clinical negligence cases where the appropriateness of the management in labour of known GBS colonisation has been questioned and the issue of whether the inappropriate management led to or worsened the infection in the baby has been raised.
I have also acted in cases where the management of the baby after birth has not been adequate.
Obviously, the management of GBS colonisation in pregnancy, and particularly in labour, is a matter for an obstetrician as well as a neonatologist. Cases in this area highlight firstly, the importance of joint working across specialities in clinical negligence cases and secondly, where management of a condition in pregnancy potentially has serious subsequent effects on the baby.
The appropriate treatment for known colonisation in pregnancy is to give antibiotics to the mother in labour; termed Intrapartum Antibiotic Prophylaxis (IAP). The timing, adequacy and appropriateness of IAP can raise questions in clinical negligence cases.
Terminology: early versus late onset infection
The terms early versus late-onset infection can cause confusion; particularly in terms of the impact of treatment in labour on the subsequent development of infection in the baby.
It should be noted there are other bacteria that can cause life threatening infection in babies but GBS is the commonest single cause.
Early-onset GBS Infection – the majority of early-onset infection presents within 24 hours of birth but can occur, by definition up to and including Day 6 of life. Approximately two thirds of GBS infection in babies are early onset.
Late-onset GBS Infection – occurs from Day 7 onwards up until 3 months of age.
Serious GBS infection can frequently be associated with meningitis which can, on occasions cause significant brain damage resulting in cerebral palsy and lifelong complex medical needs for the child.
GBS carriage is common (20-40% of women in the U.K.) and without antibiotics 50% of affected newborn babies would be colonised, however only 1-2% of these would go on to develop symptoms of serious infection.
The overall incidence of serious or invasive GBS infection is 0.5/1000 births but varies across the world. The incidence in some countries such as the USA has declined significantly over recent years, in the main due to routine screening for GBS in pregnancy and subsequent extensive use of IAP. However this approach must be balanced against the potential harm of vast numbers of women receiving antibiotics in labour. Unlike in the USA, in the UK women are not routinely tested for GBS in pregnancy; a risk factor based approach is used.
The treatment of a GBS positive mother in labour, with antibiotics impacts only on the prevention of early onset not late onset disease; it has been stated by experts in the field that there is “no effective approach to the prevention of late onset disease”.
How should GBS carriage in pregnancy be treated in labour to reduce the risk of disease in the newborn?
There is clear guidance from NICE: Group B Streptococcal Disease, Early-onset on which women colonised with GBS should be treated in pregnancy. It also covers where treatment has been inadequate in labour (for example if labour progressed more rapidly than expected and a full course of antibiotics could not be delivered) and what treatment should be given to the baby.
Such management however would not then prevent a baby developing late onset GBS infection.
It should be noted that any baby who is unwell, regardless of a history of GBS carriage or not should be treated as a precaution for infection at least until the infection tests are returned as negative as infection in full term newborns is one of the common causes (along with cardiac defects and metabolic disorders) of unexpected collapse in the hours and days after birth.
- GBS can cause potentially devastating infection in newborn infants with a mortality rate of 10%.
- One of the key factors in preventing early onset disease is the appropriate management of the carriage of GBS in pregnancy and an area where errors are often made.
- Any baby at risk of GBS sepsis should be promptly and appropriately treated and in any unwell baby after birth, bacterial infection should be considered as a potential cause
- There is clear national guidance from the National Institute of Clinical Excellence as to how GBS carriage in pregnancy and early onset infection should be managed. (Group B Streptococcal Disease, Early-onset. Green-top Guideline No. 36)
- Late onset infection (after Day 6 of life) is not impacted by Intrapartum Antibiotic Prophylaxis in labour