ST-26 serotype V Group B Streptococcus: an unexpected lineage among maternal carriage strains and neonatal infection in Gabon

Background To investigate the burden of neonatal Group B Streptococcus (GBS) infection, we conducted a prospective study at a regional hospital in Gabon. Methods Consecutive parturients and their newborns were enrolled in this study. Vaginal swabs were collected and cultured to test for GBS colonization. Blood cultures were obtained from newborns presenting clinical signs suggestive of infection during the first 28 days of life. All GBS strains underwent whole-genome sequencing. Results A total of 203 newborns and 197 mothers were enrolled. One newborn developed GBS disease, corresponding to an incidence of 4.93 cases per 1,000 live births. Vaginal GBS colonization was detected in 28 parturients (14.2%). Seven colonizing strains (25.0%) and the neonatal strain belonged to clonal complex CC26. Conclusion These initial data on the molecular epidemiology of maternal GBS colonization and neonatal infection in Gabon reveal an unexpected contribution of CC26 strains, a lineage that has been rarely reported in this context.