Seroepidemiologic studies of serotype VIII group B Streptococcus in Japan.

Levels of antibody to serotype VIII group B Streptococcus (GBS) were surveyed in serum samples from 583 pregnant women, from 461 neonates born to these women, and from 4 mother-and-neonate pairs with early-onset serotype VIII sepsis. Colonization by serotype VIII GBS was associated with significantly higher serum concentrations of serotype-specific antibodies (geometric mean [GM], 5.53 micro g/mL), compared with both noncolonization (1.53 micro g/mL) and colonization with other serotypes (2.19 micro g/mL). There was excellent correlation between antibody levels in mothers and those in their neonates. The prevalence of positive antibody levels, when arbitrarily defined, according to antibody levels in neonatal sepsis (GM, 0.49 micro g/mL) as >1.0 micro g/mL, was 58% of all pregnant women and 85% of the women colonized by serotype VIII. This high serotype prevalence may explain, at least in part, why serotype VIII causes early-onset neonatal disease at rates lower than those which would be expected on the basis of its prevalence in mothers in Japan who are colonized by GBS.