COMPARATIVE-STUDIES ON STREPTOCOCCI OF SEROLOGICAL GROUP-G ISOLATED FROM VARIOUS ORIGINS

The streptococcal cultures used in the present study were isolated fro m dogs, bovines and humans and could be classified into Lancefield's s erological group G. Most of the group G streptococci grew in fluid med ia as granular sediment with clear supernatant and formed compact colo nies in soft agar. The majority of the group G streptococci from dogs and bovines displayed CAMP-like synergistic haemolytic activities on s heep brood agar, fermented lactose and salicin and produced the enzyme alpha-D-galactosidase. The group G streptococci from humans mainly fe rmented trehalose and produced the enzyme beta-D-glucuronidase. In add ition, some of the group G streptococci reacted with type antigen X an d R and two cultures with MG specific antiserum. A positive opacity fa ctor reaction could be observed with few group G streptococci isolated from dogs and bovines, but not with those from humans. In binding stu dies with I-125-labelled plasma proteins most of the cultures interact ed with I-125-immunoglobulin G and I-125-albumin. Binding of I-125-IgG was more pronounced among group G streptococci isolated from humans. The determination of antibiotic susceptibility revealed that most of t he group G streptococci were susceptible to bacitracin, cefoxitin, cli ndamycin, erythromycin, gentamicin, penicillin and sulfamethoxazole-tr imethoprim. Some of the cultures were resistant to minocycline, neomyc in and tetracycline. All this data clearly distinguished group G strep tococci isolated from animals and humans and could additionally be use d for individual characterization of this microorganism. This might be useful in epidemiological aspects and contribute to understanding inf ections caused by these bacteria.