GBS STUDY: Assessing disease burden and risk factors for neonatal group B streptococcal infection to inform the best strategies to prevent life threatening infections in newborns

Abstract

This body of work arose from everyday challenges that paediatricians and neonatologists have working in the field of general paediatrics and neonatology regarding the implementation and use of the universal Group B Streptococcal (GBS) Screening and Management Guidelines. Despite universal screening programs for maternal GBS colonisation in pregnancy that have been instituted across hospitals in Australia, neonatal GBS infection remains the most common cause of infectious neonatal morbidity and mortality. This bacterium can illicit early onset disease occurring in the first week of life of the neonate, or late-onset disease occurring anywhere after the first week of life, up to the first three months causing major mortality and morbidity, often presenting as neurodevelopmental sequelae in affected infants. In Australia, most of our states and territories have adopted a version of the universal screening approach of pregnant mothers during week 35-37 of their pregnancy, for GBS colonisation. Depending on individual risk factors, maternal antibiotic prophylaxis is offered to mothers in labour in order to prevent neonatal GBS disease. Despite the universal recommendations to screen and manage this disease, the guidelines are often followed sporadically and left up to the clinician’s discretion. There is also a concern that the widespread use of maternal antibiotic prophylaxis is increasing worldwide antibiotic resistance of GBS strains and may lead to unwanted health issues in the longer term for the infant (such as increasing atopic and gastrointestinal disease). The first publication, ‘GBS Study Protocol’, describes the novel study design implemented for the comprehensive collection of retrospective data over a 16-year period across 5 hospitals in South Australia and the Northern Territory. Currently, notification of Group B streptococcal infections in the young infant is not mandatory. As a result, the true incidence of early onset and late onset GBS disease is not known in Australia. This case-control study was designed to measure the true incidence of both early onset and late onset GBS disease over the last 16 years in South Australia (SA) and the Northern Territory (NT) and to identify any maternal and neonatal risk factors for disease (see Appendix for data collection tools). The second publication, ‘GBS Case-Control Study’, reports the outcomes of the case control study. A primary objective of this study was to determine maternal and neonatal risk factors for GBS neonatal infection in the SA and NT between the years 2000 to 2015. A further primary objective is to measure the incidence of GBS neonatal infection in SA and the NT for early-onset GBS disease (disease in the first 7 days of life) and late-onset GBS disease (disease occurring after 7 days to 90 days of life), as well as to comment on the clinical features and burden of GBS disease. The SA incidence of probable and confirmed cases of early onset GBS was found to be 32 per 100,000 live births and of late onset GBS was 17.8 per 100,000 live births; and NT incidence of early onset GBS was 90 per 100,000 live births and 17.8 per 100,000 live births for late onset GBS. This information will assist in determining whether a future GBS vaccination program should be recommended for pregnant mothers in the future. This large study conducted at five hospital sites, required the participation of several site supervisors and data collectors, with Human Research Ethics Committees approvals obtained at each site including the SA Aboriginal Human Research Ethics Committee approval (see Appendix for Human Research Ethics committee approval forms).