Properties and type antigen patterns of group B streptococcal isolates from pigs and nutrias.

All 59 group B streptococcal cultures isolated from pigs and nutrias reacted with group B-specific antiserum and gave a positive CAMP reaction in the zone of staphylococcal beta-lysin. Most of the cultures were pigmented; all cultures hydrolyzed Na hippurate and utilized salicin, maltose, and saccharose but not esculin, mannitol, or inulin. Fifty-three percent of the group B streptococci from pigs and none of those from nutrias were lactose positive. Serotyping revealed that most of the group B streptococci from pigs were of serotype III and most of those from nutrias were of type Ia/c. Protein c was present as c beta antigen. All group B streptococci were susceptible to penicillin and bacitracin (10 U), and most of the porcine cultures were resistant to tetracycline. According to these results, group B streptococci from pigs and nutrias differ from bovine and human group B streptococci and seem to play no role in cross-infections between animals or between animals and humans.