Virulence factors of Streptococcus agalactiae relating to neonatal sepsis

Abstract

Streptococcus agalactiae (Group B Streptococcus, GBS) infection is the leading cause of disease in neonates. Infection in the neonate can occur via vertical transmission or ascension through the vaginal tract. After ascension, infection of the amniotic fluid occurs via several virulence factors which allow for invasion of the placental membrane and chorioamniotic membranes. Neonatal infection is categorized into either early-onset sepsis or late-onset sepsis, with both being able to result in severe illness or even death. Prevention of GBS infection in the mother and neonate to this point includes neonatal screening at 35-37 weeks and treatment in GBS positive patients with IV penicillin. In those with allergies, cefazolin or clindamycin may be substituted. Documented increases in antibiotic resistance have led to the need for further research surrounding virulence factors. This outline summarizes several virulence factors including the hemolytic pigment, hyaluronidase, pili, adhesins, and the sialic rich capsular polysaccharide, that have been identified as key to colonization and infection of the neonate. Understanding of the virulence factors and incorporating prior deletion studies allows for advancements in treatment and prevention to be made. Novel theories will open the door for further research towards implementation of a vaccine as a means for preventing colonization.

Keywords

• streptococcus
• agalactiae
• neonates
• vaginal tract