Variation in the number of tandem repeats and profile of surface protein genes among invasive group B Streptococci correlates with patient age.

The average number of tandem repeats of the rib gene (which encodes the Rib surface protein) in invasive group B streptococci from 29 neonates was smaller than that from 20 adults (6.8 and 8.6, respectively; P<0.05), implying a distinct contribution of immunity toward this age-related variation.