Temporal Changes in Invasive Group B Streptococcus Serotypes: Implications for Vaccine Development

Abstract

IntroductionThere is a paucity of longitudinal data on the serotype-specific burden of invasive group B Streptococcus (GBS) disease from low-middle income countries, which could inform selection of vaccine epitopes.MethodsFrom 2005 to 2014, infants less than 90 days of age with invasive GBS disease were identified through sentinel laboratory and hospital admission surveillance at Chris Hani Baragwanath Academic Hospital in Soweto, South Africa.ResultsWe identified 820 cases of invasive GBS disease, including 55% among newborns <7 days age (i.e. early-onset disease; EOD). The overall incidence (per 1,000 live births) of invasive GBS disease was 2.59 (95% CI: 2.42–2.77), including 1.41 (95% CI: 1.28–1.55) for EOD and 1.18 (95% CI: 1.06–1.30) in infants 7–89 days age (late-onset disease). Year-on-year, from 2005 to 2014, we observed a 9.4% increase in incidence of serotype Ia invasive disease (RR: 1.09; 95% CI: 1.04–1.15; p<0.001), and a 7.4% decline in serotype III invasive disease (RR: 0.93; 95% CI: 0.90–0.96; p<0.001). Overall, serotypes Ia (28.2%), III (55.4%) and V (7.9%) were the commonest disease causing serotypes.ConclusionsThe incidence of invasive GBS disease has remained persistently high in our setting, with some changes in serotype distribution, albeit mainly involving the same group of dominant serotypes.

Antimicrobial susceptibility and serotype distribution of Streptococcus agalactiae recto-vaginal colonizing isolates from pregnant women at a tertiary hospital in Pretoria, South Africa: an observational descriptive study

“…This study showed that serotypes Ia (54%), III (20%) and V (16%) were the predominant serotypes which is in concordance with other studies conducted among pregnant women in South Africa [5]. Serotypes Ia and III together accounted for 74% of the colonised population in our study, whilst the 3 dominant serotypes accounted for 90% of all cases.…”

“…These results are in keeping with another South African study which showed that serotype III is the commonest cause of EOD in South Africa, accounting for 41.4% of all cases, whilst serotype Ia accounted for 34.7% of cases [5]. The majority of invasive disease was caused by serotypes Ia, III and V [5]. These 3 serotypes are included in a pentavalent polysaccharide protein conjugate vaccine currently being developed and is in a phase 1 trial [17].…”

“…Serotypes Ia and III together accounted for 74% of the colonised population in our study, whilst the 3 dominant serotypes accounted for 90% of all cases. These results are in keeping with another South African study which showed that serotype III is the commonest cause of EOD in South Africa, accounting for 41.4% of all cases, whilst serotype Ia accounted for 34.7% of cases [5]. The majority of invasive disease was caused by serotypes Ia, III and V [5].…”

“…Ia, Ib and II-IX. The distribution of the five most common GBS serotypes in South Africa causing invasive disease are III-55.4%, Ia-28.2%, V-7.9%, II-3.6% and Ib-3.4%, II-5% [5]. This compares similarly to the global distribution [6].…”

Knowledge gaps among South African healthcare providers regarding the prevention of neonatal group B streptococcal disease

“…In this setting, the burden of early-onset neonatal sepsis is estimated as 35.6 per 1000 live births, and 10% of cases are associated with bacteraemia, with GBS being the most commonly identified pathogen [ 8 ]. We have previously reported a high (and largely unchanged) incidence of EOD (1.41; 95% CI: 1.28–1.55) [ 3 , 9 ]. This is most likely attributable to the poor implementation of the risk-based strategy: only 26% of pregnant women with risk factors actually receive IAP timeously [ 10 ].…”