Abstract
BackgroundMother-to-baby transmission of group B Streptococcus (GBS) is the main cause of early-onset infection. We evaluated whether, in women with clinical risk factors for early neonatal infection, the use of point-of-care rapid intrapartum test to detect maternal GBS colonisation reduces maternal antibiotic exposure compared with usual care, where antibiotics are administered due to those risk factors. We assessed the accuracy of the rapid test in diagnosing maternal GBS colonisation, against the reference standard of selective enrichment culture.MethodsWe undertook a parallel-group cluster randomised trial, with nested test accuracy study and microbiological sub-study. UK maternity units were randomised to a strategy of rapid test (GeneXpert GBS system, Cepheid) or usual care. Within units assigned to rapid testing, vaginal-rectal swabs were taken from women with risk factors for vertical GBS transmission in established term labour. The trial primary outcome was the proportion of women receiving intrapartum antibiotics to prevent neonatal early-onset GBS infection. The accuracy of the rapid test was compared against the standard of selective enrichment culture in diagnosing maternal GBS colonisation. Antibiotic resistance profiles were determined in paired maternal and infant samples.ResultsTwenty-two maternity units were randomised and 20 were recruited. A total of 722 mothers (749 babies) participated in rapid test units; 906 mothers (951 babies) were in usual care units. There was no evidence of a difference in the rates of intrapartum antibiotic prophylaxis (relative risk 1.16, 95% CI 0.83 to 1.64) between the rapid test (41%, 297/716) and usual care (36%, 328/906) units. No serious adverse events were reported. The sensitivity and specificity measures of the rapid test were 86% (95% CI 81 to 91%) and 89% (95% CI 85 to 92%), respectively. Babies born to mothers who carried antibiotic-resistant Escherichia coli were more likely to be colonised with antibiotic-resistant strains than those born to mothers with antibiotic-susceptible E. coli.ConclusionThe use of intrapartum rapid test to diagnose maternal GBS colonisation did not reduce the rates of antibiotics administered for preventing neonatal early-onset GBS infection than usual care, although with considerable uncertainty. The accuracy of the rapid test is within acceptable limits.Trial registrationISRCTN74746075. Prospectively registered on 16 April 2015
Highlights
Mother-to-baby transmission of group B Streptococcus (GBS) is the main cause of early-onset infection
There was no evidence of a difference in the rates of intrapartum antibiotic prophylaxis between the rapid test (41%, 297/716) and usual care (36%, 328/906) units
Babies born to mothers who carried antibiotic-resistant Escherichia coli were more likely to be colonised with antibiotic-resistant strains than those born to mothers with antibiotic-susceptible E. coli
Summary
Mother-to-baby transmission of group B Streptococcus (GBS) is the main cause of early-onset infection. In order to prevent neonatal early-onset GBS infection, pregnant women colonised with GBS are offered antibiotics intrapartum, ideally at least 4 h before childbirth [4, 5]. Many countries, such as the USA, have national screening programmes that use culture-based tests to identify women colonised with GBS in late pregnancy [6]. Culture-based tests at 35–37 weeks of gestation have limited accuracy in predicting the maternal GBS colonisation status in labour [7, 8], take up to 48 h to produce a result, and are likely to be missed in women who go into labour preterm
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