Screening for Group B streptococcus should be routine in pregnancy: FOR: The case for screening

In the 1970s, early-onset group B streptococcus disease (EOGBSD) was identified as the major infectious cause of first-week neonatal morbidity and mortality in the USA. From the 1980s, clinical trials showed that administering intravenous penicillin prevented up to 90% of such cases. The American Congress of Obstetricians and Gynecologists (ACOG) issued recommendations for intrapartum antibiotic prophylaxis (IAP) in 1996, and in 2002 they recommended universal culture-based screening of all pregnant women at 35–37 weeks of gestation. During this time, the incidence of EOGBSD fell from >1.5 cases/1000 live births to <0.4 cases/1000 live births, as explained in the 2010 guidelines from the US Centers for Disease Control and Prevention report (www.cdc.gov/mmwr/preview/mmwrhtml/rr5910a1.htm). Similar falls have been seen in other countries/regions that have introduced routine screening and IAP, such as Canada, Australia and New Zealand, France, Germany, Spain, Belgium, Italy, Poland, Argentina, Chile, Kenya, Hong Kong, Oman and Japan (there are more). In contrast, since 2003 the Royal College of Obstetricians and Gynaecologists (RCOG) has continued to recommend a risk-based approach in the UK, even though this has not been associated with a fall in the incidence of EOGBSD in England (it remains at about 0.36 cases/1000 live births, which equates to about 400 cases per year). The average incidence per thousand in Northern Ireland is about 0.51, in Scotland is 0.36 and in Wales is 0.32, highlighting local variations in incidence (the incidence can be as high as 0.88–1.15/1000; G. Rao, Northwick Park and Luton Hospitals, pers. comm.). If the incidence fell by 75%, as expected from the experience of other countries, this would save 300 families per year in the UK the trauma of dealing with EOGBSD. But would screening in the UK be cost effective? Colbourn et al. (BMJ 2007;335:655) concluded that ‘culture testing for low risk term women, while treating all preterm and high risk term women, would be the most cost effective option’, while Kaambwa et al. (BJOG 2010;117:1616–27) wrote that, ‘The current strategy of risk-factor-based screening is not cost-effective compared with screening based on culture’. The cost of the enhanced culture medium (ECM) testing of low vaginal and rectal swabs is estimated at £11, and the swabs can be performed by the women themselves if they choose screening. Concerns have been expressed about penicillin allergy, but true anaphylaxis is rare. Law et al. (J Med Screen 2005;12:60–68) reported that there were no recorded deaths in the first 1.8 million women given IAP in the USA, and other reports have stressed that giving IAP under direct supervision is very safe. Concern has been expressed about the practice of giving women (and therefore their fetuses) large doses of broad-spectrum antibiotic before skin incision for caesarean section, as currently recommended by the RCOG, in terms of the effect it might have on the development of the newborn's immune system. In contrast, penicillin is narrow spectrum, GBS has never developed resistance to it and there is no evidence that preventing EOGBSD encourages other organisms to invade. The widespread use of penicillin for over 60 years means that any organisms able to become resistant to it are likely to have already done so. Current RCOG guidelines recommend giving IAP if a woman is found serendipitously (on a swab for vaginal irritation, for example) to be a GBS carrier. On grounds of equity and choice, pregnant women at 35–37 weeks of gestation should be offered an equal opportunity to determine their GBS status and protect their babies, which can only be achieved by screening. Philip Steer chairs the medical advisory committee of Group B Strep Support, which campaigns for GBS screening to be universally available. ■

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