A Unique Child: Health - A doctor's diary ... Group B strep
Dr Raj Thakkar
Monday, July 11, 2011
'Doctor, my friend's son has been admitted to hospital with a severe bacterial infection called Group B strep. I'm heavily pregnant - could my baby get it?'
A third of people will have Group B streptococcus (GBS) in their intestine, and a quarter of women have it in their vagina at any given time. Colonisation is intermittent, and for most, has no consequences. In contrast, infection with GBS carries significant morbidity and mortality. While infection can occur in any age group, infants aged up to three months are most susceptible and, indeed, GBS is the most common cause of life-threatening infection in newborn babies.
Compared with countries who screen for GBS in pregnant women, the UK incidence of so-called early onset GBS (EO GBS) infection has been shown to be increasing and varies from less than one, to 3.6 per 1,000 live births. Of the 230,000 babies born to GBS-positive mothers in the UK, without preventative medicine around 88,000 will be colonised, 700 will suffer severe infection and up to 100 will die. GBS can also cause stillbirth and premature labour.
TYPES
Currently in the UK, 75 per cent of GBS infection is of the early onset type, defined as infection occurring between nought and six days of life. Babies acquire the GBS bacteria from a colonised mother during labour.
Children may present to their doctor with pneumonia, meningitis or blood poisoning suggested by respiratory distress, poor feeding, excess sleepiness, irritability, low blood sugar, cold peripheries or difficulties in maintaining a normal heart rate and blood pressure. EO GBS carries an 11 per cent mortality risk and children who survive are at risk of complications.
In contrast, late onset GBS (LO GBS) infection occurs seven or more days after birth and may be contracted through a variety of sources. LO GBS infection is rare beyond three months of age. Five per cent of babies who develop LO GBS infection die, usually from meningitis or blood poisoning. Of those who survive meningitis, half will have brain damage. Unlike EO GBS, screening has not reduced the incidence of LO GBS.
RISK FACTORS
Risk factors for infants contracting EO GBS can be the mother having a previous baby with GBS infection, if she is found to have GBS on vaginal swabs or in the urine during the current pregnancy, if she goes in to labour early, if her waters break prematurely or if she has a fever.
A 60 per cent reduction in EO GBS infection may be achieved by offering antibiotics to high-risk women during labour. Despite this guidance, policy regarding GBS varies across the UK and some obstetric units do not have a GBS policy.
In addition, not all women who are identified as high-risk receive intra-partum antibiotics. Furthermore, the risk factor in many women may only be colonisation, so without swabbing women in pregnancy, which is currently not done routinely in the UK, a significant number of cases will not be identified.
As the incidence of GBS infection in the UK rose between 2003 and 2007, it is clear that a change in current policy is required. There has been a significant reduction in the incidence of EO GBS infection in countries such as the US, Australia, Spain, France, Italy and Belgium, which screen pregnant women for GBS between 35 and 37 weeks' gestation.
By offering antibiotics during labour to pregnant women who are colonised with GBS as well as those whose babies are risk of infection, over 90 per cent of GBS infections could be prevented.
Current arguments
Despite the arguments for screening, the National Institute for Health and Clinical Excellence (NICE) and the Screening Committee have not endorsed a UK-wide GBS screening programme; one reason is cost-effectiveness. To complicate matters further, swab samples cultured using standard methods available on the NHS are able to identify only 50 per cent of positive cases.
Private tests are available, which are highly sensitive but more expensive than NHS ones. Testing should take place between 35 and 37 weeks' gestation. Testing before this time may miss subsequent colonisation, whereas testing beyond 37 weeks may not allow enough time to process the results before the birth. Details of these tests and further information may be found at the website of the Group B Strep Support Group at www.GBSS.org.uk.
Awareness of GBS among healthcare professionals and pregnant women in the UK is considered inadequate. Surveys have shown 90 per cent of women would pay for private GBS testing if they were made aware of it. It is clear, given the increasing incidence of GBS infection in the UK, that urgent action is required.
MORE INFORMATION
- July is International Group B Strep Awareness Month. For more information see www.groupbstrepinternational.org
- Group B Strep Support: www.gbss.org.uk
Dr Raj Thakkar BSc(Hons) MBBS MRCGP MRCP(UK) is a full-time GP in Buckinghamshire
