Table 1 Hemolytic titers of GBS strains isolated from rectovaginal swabs of women in their third trimester of pregnancy.

COH1 is a wild-type GBS clinical isolate from an infected newborn and belongs to the hypervirulent ST-17 clone. COH1ΔcovR is a mutant derived from COH1 and exhibits increased hemolytic activity. Strains #65 and #91 are rectovaginal GBS isolates that exhibit increased hemolysis and decreased CAMP factor expression similar to COH1ΔcovR (see fig. S1).

StrainHemolytic titer
Clinical isolates
  Wild-type GBS (COH1)2
Rectovaginal isolates
  Strain #65>32
  Strain #91>32
  Remaining 51 isolates≤2