Experimental induction of bovine mastitis with human strains of group B streptococci (streptococcus agalactiae).

Intrapapillary deposition of 5-30 CFU of 6 separate human strains of Group B streptococci into 7 lactating quarters of 6 cows resulted in clinical mastitis in all. Identical streptococci were subsequently recovered from 6 of the affected quarters. Details of milk somatic cell counts, bacterial isolations and clinical findings are tabulated. The role of GBS in human medicine and the implications of proof that the bovine udder is susceptible to small numbers of GBS from human sources, are discussed.