Experimental infection with group B streptococci in tissue cages implanted in rabbits

Using tissue cages subcutaneously implanted in rabbits an experimental group B streptococcal (GBS) infection was induced. The type Ia strain differed from the type III strain in producing a septicemic infection leading to the death of the animals on day 4 of infection. Active immunization with whole cells of the homologous strain resulted in phagocytosis and killing of the bacteria, whereas passive immunization only resulted in inhibition of the spread of the type Ia infection from the cages. Electron microscopy showed that in unprotected animals infection with either strains was followed by a lysis of erythrocytes and polymorphonuclear cells in the cage fluid. Opsonization by type-specific antibodies already present in the cage fluid preceded the phagocytosis of streptococci in the immunized animals. The tissue cage model offers a suitable way for studies of the pathogenesis of GBS infection. The different factors influencing the process of infection can also be easily monitored.