Association between antibodies against group B Streptococcus surface proteins and recto-vaginal colonisation during pregnancy

Sonwabile Dzanibe, Gaurav Kwatra, Peter V. Adrian, Sheila Z. Kimaro-Mlacha, Clare L. Cutland, Shabir A. Madhi
2017 Scientific Reports  
Group B Streptococcus (GBS) recto-vaginal colonisation in pregnant women is the major risk factor for early-onset invasive GBS disease in their newborns. We aimed to determine the association between serum antibody levels against 11 GBS surface proteins and recto-vaginal acquisition of GBS colonisation during pregnancy. Sera collected from pregnant women at 20-25 weeks and ≥37 weeks of gestation age were measured for IgG titres against GBS surface proteins using a multiplex immunoassay. Women
more » ... re evaluated for recto-vaginal colonisation every 4-5 weeks. We observed that the likelihood of becoming colonised with GBS during pregnancy was lower in women with IgG titres ≥200 U/mL against gbs0233 (adjusted OR = 0.47 [95% CI: 0.25-0.89], p = 0.021) and ≥85 U/mL for gbs1539 (adjusted OR = 0.44 [95% CI: 0.24-0.82], p = 0.01) when comparing between women who acquired GBS colonisation and those that remained free of GBS colonisation throughout pregnancy. IgG titres (U/mL) specific to BibA and Sip were higher in pregnant women colonised with GBS (380.19 and 223.87, respectively) compared to women with negative GBS cultures (234.42 and 186.21, respectively; p < 0.01) at ≥37 weeks gestation. Antibodies induced by gbs0233 and gbs1539 were associated with a reduced likelihood of recto-vaginal GBS acquisition during pregnancy and warrant further investigation as vaccine targets. Group B Streptococcus (GBS) is a leading cause of invasive bacterial disease in the first seven days of life (i.e. early-onset diseases; EOD) 1 , with 90% of the cases occurring within the first 24 hours of life 2,3 . Recto-vaginal GBS colonisation during pregnancy is the strongest independent risk factor associated with EOD, in which colonised pregnant women vertically transmit GBS to their newborns either in utero or intrapartum. About 10-30% of women are colonised with GBS in the gastrointestinal and genitourinary tract, with colonisation occurring in an intermittent, transient and persistent manner during pregnancy 4-6 . GBS colonisation in the genitourinary tract of women also causes clinical and subclinical acute infections, including chorioamnionitis, endometritis and urinary tract infections 7 . Moreover, GBS colonisation during pregnancy is associated with, late miscarriages, premature birth and stillbirths 8 . Intrapartum antibiotic prophylaxis (IAP) treatment of women colonised with GBS at 35-37 weeks of gestation age is the recommended strategy to reduce vertical transmission. Since the adoption of IAP treatment in high-income settings, the number of reported EOD cases has declined by 80% 9,10 , however, such a strategy remains logistically challenging and unlikely to be cost-effective for low-income countries, including in settings where 40-60% of deliveries occur outside of health-care settings 11, 12 . Alternative strategies to prevent EOD and other GBS related pregnancy complications are being studied, such as maternal immunisation during pregnancy using GBS capsular polysaccharides (CPS) conjugated to carrier
doi:10.1038/s41598-017-16757-9 pmid:29184151 pmcid:PMC5705700 fatcat:qnjoovhtyvh43bb5gbqtyqwyuq