Group B Strep Support replies to Margaret McCartney

We of Group B Strep Support (GBSS) were disappointed that Margaret McCartney reiterated some myths about screening for group B streptococcus during pregnancy.1 We challenge four of her statements.

(1) “The risks of antibiotic use include anaphylaxis, which is thought to be fatal in one in 10 000 women treated.”

This is an unreferenced statement from the UK National Screening Committee’s 2008 review of antenatal screening for streptococcus B. Fatal anaphylaxis is extremely rare. Law et al reported that 1.8 million women in the US were given benzylpenicillin (or ampicillin) between 1997 and 2001 with no deaths from anaphylaxis reported.2 Their review of UK data showed no adverse drug reactions attributable to benzylpenicillin in a population of 630 000 over six months. They conclude that the risk of death is negligible.

(2) “Broad spectrum antibiotics lead to resistant organisms . . . The potential for long-term persistence of early-colonising bacteria suggests that much more thought should be given to the late consequences of perinatal broad-spectrum antibiotics.”

This is of great concern to GBSS’s medical advisory panel, one of whom (ABR) coauthored an article quoted by McCartney (and has responded separately with her co-author).

Studies in the US have not shown an increase in antibiotic resistance in response to antibiotics for early onset prophylaxis against streptococcus B except in very low birth weight babies; resistant Escherichia coli infection was increased in those whose mothers were given amoxicillin. Anxieties raised by the ORACLE II study follow-up findings of increased cerebral palsy at age 7 applied only to babies of women in threatened preterm labour given broad spectrum antibiotics for up to 10 days, not to those of women given high dose intravenous benzylpenicillin for 4-12 hours in established labour (the ORACLE I study of antibiotics given to women with ruptured membranes did not show any functional impairment at age 7).

(3) “In several of the case studies in the media stories, the screening test for streptococcus B would not have helped.”

This may be true, but the policy recommended by cost benefit analyses is to screen at 35-37 weeks and give benzylpenicillin to all women in preterm labour. This policy is applied in countries that screen, including the US, Australia, France, and Spain, where the incidence of early onset streptococcus B infection has reduced on average by over 80%.3

(4) “It may be that risk management rather than universal screening is more beneficial but will require nuanced discussion.”

Perhaps, yet research repeatedly finds universal screening more cost and clinically effective for the UK than the risk based strategy, even ignoring the inconsistent application of the Royal College of Obstetricians and Gynaecologists’ 2003 guidelines. A recent UK study showed that 81% of mothers who should have been offered intrapartum antibiotic prophylaxis because of risk factors were not, with an estimated 48% of babies developing avoidable early onset streptococcus B infection.4 A risk based strategy may be too complex—any effective strategy needs to be easy to understand and implement.

The potential benefits of screening are reduced morbidity and mortality from early onset streptococcus B infection. Countries implementing screening strategies show substantial reductions in incidence. The UK incidence has risen since the Royal College of Obstetricians and Gynaecologists’ 2003 risk based prevention guidelines were introduced, and it continues to do so. The Health Protection Agency found that voluntarily reported cases in England, Wales, and Northern Ireland rose from 229 in 2003 to 302 in 2010.5 The incidence is now 0.41 per 1000 live births, higher than in the US after universal screening (0.34 per 1000 live births in 2008).

It is in everyone’s interest to explore fully the issues around screening, presenting information about potential benefits and harms equally accurately. The public consultation on the review of streptococcus B screening by the UK National Screening Committee starts in June 2012, and we should all ensure that the relevant issues are explored appropriately, supported by research. Recently the committee agreed to pilot screening for maple syrup urine disease, saving perhaps seven lives a year,6 yet streptococcus B has a much higher incidence and mortality.

GBSS wants women to be given accurate information about streptococcus B and offered a sensitive test for carriage late in pregnancy. They should not be forced into screening, rather they should be entitled to information, sensitive testing, and the option to say yes or no. Wouldn’t it be great if we could agree evidence based information and give women a proper choice? Revolutionary even.