Commentary

Group B Streptococcus (GBS) is a leading cause of neonatal early-onset sepsis (EOS) and infection-attributable neonatal mortality worldwide. Disease incidence has declined in the USA over the past 30 years, largely due to implementation of preventative strategies. The American College of Obstetricians and Gynecologists currently recommends pregnant individuals undergo antenatal culture-based screening for GBS carriage and receive intrapartum antibiotic prophylaxis (IAP) if GBS-colonised.1 Recommendations for neonatal EOS risk assessment from the American Academy of Pediatrics include consideration of maternal GBS colonisation as well as administration of adequate IAP, defined as maternal receipt of ampicillin, penicillin, or cefazolin at least 4 hours prior to birth.2

IAP use to prevent neonatal GBS disease evolved from the recognition that newborns only suffered GBS infection when their mothers were colonised with GBS in the vaginal-rectal tract, and that such colonisation was only present in approximately 20% of US pregnant individuals. Therefore, if maternal colonisation could be eliminated, then theoretically neonatal disease could be avoided. Efforts to administer oral antibiotics during pregnancy failed to eradicate maternal GBS carriage or were complicated by high recolonisation rates at the time of childbirth. In 1979, Yow and colleagues described the results of administering intrapartum intravenous ampicillin to 34 GBS-colonised parturients compared with 24 untreated but colonised controls.3 As assessed by cultures from ear, throat, umbilicus and rectal neonatal sites, 14 out of 24 (58%) newborns of untreated parturients were GBS-colonised but 0 out of 34 newborns of ampicillin recipients were GBS-colonised. Notably, 30 out of 34 treated parturients received only a single dose of ampicillin. The authors performed detailed studies in two treated …