Incidence of Group B Streptococcus bacteraemia in mum and newborn following antimicrobial prophylaxis- To screen or not to screen?

Abstract

Introduction There is no routine screening for antenatal Group B Streptococcus (GBS) carriage in the UK. However invasive GBS in newborns, whilst rare (0.57/1000 births), is associated with mortality (5%) and long-term disability (9%). Antimicrobialsperi-partum can reduce the risk of invasive infection. Method We undertook a retrospective observational study at a London teaching hospital to investigate the incidence of invasive GBS peri-partum in both mother and child between 1/4/16 and 31/3/19. Results There were 16,869 live births recorded at Chelsea & Westminster Hospital during the study period. Operative, caesarean and spontaneous delivery accounted for 16.7%, 34.9% and 48.2%; with incidence of neonatal GBS bacteraemia being 0.18%, 0.08% and 0.11%, respectively. 20 (0.12%) neonates had invasive GBS infections, with 7/20 neonates having concurrent maternal GBS bacteraemia. 34(0.22%) ladies had GBS bacteraemia peri-partum; none had GBS isolated prior to delivery. 543 women had a positive GBS clinical isolate prior to labour;69.1% received GBS prophylaxis peri-partum with no invasive GBS transmission. Despite no prophylaxis in 168/543 GBS colonised women, no invasive GBS neonatal cases were identified. Conclusions Our local data identifies a low prevalence (0.12%) of invasive GBS infection in newborns. Maternal GBS bacteraemia is more frequently observed and associated with concurrent newborn GBS bacteraemia. Antimicrobial prophylaxis adherence peripartum although recommended is suboptimal, even though no invasive GBS transmission was identified. All invasive GBS infections were not known to be colonised pre-delivery. The current recommendations for targeting recent GBS culture do not appear to be a sensitive predictor of invasive peri-partum GBS infection.