Transposon mutagenesis of group B streptococcus beta-hemolysin biosynthesis.

Beta-hemolysin production by group B streptococci (GBS) is speculated to be a major virulence factor of the organism. A virulent, beta-hemolytic group B streptococcus strain was mutagenized with the self-conjugative transposon Tn916 to derive isogenic strains with mutations only in the gene(s) responsible for beta-hemolysin biosynthesis. There was no significant difference between the virulence of the parent strain and that of the mutant strains in a neonatal rat sepsis model.