Give your baby a better chance: Innovative testing prior to birth

Neonatal mortality due to Steptococcus agalactiae (GBS) has decreased in most populations but early onset GBS disease (EOGD) is still common in Australian Indigenous neonates. Neonatal EOGD can potentially be reduced by the introduction of a rapid test for GBS status of pregnant women during labour. The overall aim of this project was to decrease the incidence of avoidable and often-lethal GBS infections in newborns. This may have implications for improvement of the health and wellbeing of Indigenous and non-Indigenous people. Early detection of GBS in pregnant women in labour will lead to a decrease in infant mortality and a decrease in infant illnesses associated with GBS.

The primary aims of this project were:

• To optimise a GBS sensitive and specific polymerase chain reaction (PCR) test based on the model developed by Robyn Marsh in 1999. This would ensure that the test is simple to use, results can be obtained at the point of care and that the test is rapid with results being available within two hours.
• To evaluate, test, validate and demonstrate the effectiveness of this rapid PCR test in the clinical setting by collecting and testing clinical samples from women attending various hospital clinics and medical agencies
• To compare the colonisation rates of GBS within Indigenous and non-Indigenous populations.

Summary of outcomes

The PCR assay showed poor positive predictive value but it improved prevalence estimates when combined with the culture test.

• The overall prevalence of GBS was 26% with the highest rates among women attending Biala (30%) and the Mater Mothers’ public antenatal clinic (31%).
• Women with a previous history of LGT colonisation were more likely to test positive for GBS than women with no previous history of GBS colonization (p <0.001).
• All GBS serovars were detected including non-typeable strains; serotype III (46%) was the most predominant.
• The high GBS prevalence rate and the predominance of invasive serotype III in women from the Brisbane region provides valuable information that can be utilised by antenatal clinicians in the formulation of future Queensland GBS prevention policies.

Related resources:

• Thesis by Karen Taylor, A Study of Group B Streptococcus in Brisbane: The Epidemiology, Detection by PCR Assay & Serovar Prevalence PDF [5.7MB], March 2006.