Nontypable group B streptococci isolated from human sources.

The present study was done to determine whether so-called nontypable (NT) group B streptococci from human sources possess as yet unrecognized type antigens. Antisera were raised in rabbits against several NT strains and then tested with hydrochloric acid extracts of 53 NT group B streptococci. One serum was strain specific, another was nonspecific in that it contained only R-protein antibodies, and a third (NT1), although apparently type specific, reacted with only five strains. These results do not justify using NT1 serum in the group B typing system.