Group B Streptococcus virulence factors associated with different clinical syndromes: asymptomatic carriage in pregnant women and early onset disease in the newborn

Group B Streptococcus (GBS) is a leading cause of neonatal sepsis and meningitis as well as amnionitis and sepsis. Two GBS-associated syndromes are described in neonates: early-onset disease (EOD) which is responsible for 40% of cases, and late-onset disease (LOD) associated with 60% of cases. EOD occurs in the first week of life (0-6 days) and is associated mainly with bacteremia. EOD results from vertical transmission of the bacteria through contaminated amniotic or vaginal secretions of a colonized mother to her neonate during, or just before delivery. LOD occurs after the first week of life and up to the age of 3 months and is characterized by a high rate of meningitis. LOD is not necessarily associated with GBS carriage in the mother, and therefore is not attenuated by preventive strategies such as screening and antibiotic treatment of the pregnant mother. Approximately 10% of the infected babies die from GBS infection and 20% of survivors suffer permanent handicap. Since 2017, we noticed an increase in GBS associated neonatal sepsis and meningitis in Maayaney Hayeshua Medical Center (MHMC), which serves an Orthodox Jewish community in central Israel. The GBS genome is 2.2 Mbp long and has over 2,100 predicted coding regions. The bacteria have a variety of putative virulence factors that may facilitate its ability to cause disease, some of which have been identified and characterized. In this work we describe the presence of various virulence factors among 270 GBS isolates. Of these, 49 isolates underwent complete genomic sequencing. These isolates represent various Sequence Types (STs) from colonization and EOD cases. We also compared the expression level of several adhesines in colonizing GBS strains versus EOD isolate.