Characterization of group EF-4 bacteria from the oral cavity of dogs.

Samples from gingival scrapings of dogs were examined for the presence of CDC Groups EF-4 bacteria. Isolation procedures were performed in 5% sheep blood agar supplemented with thiostrepton and trimethoprim (10 mg/l). Fifty nine EF-4 strains were isolated from 92% of 49 dogs. Among the Group EF-4 bacteria, the majority of isolates belonged to the arginine-negative (biovar "b") Group EF-4 (42 strains recovered in 82% of dogs). Seventeen arginine-positive strains (biovar "a") were recovered only from 35% of dogs. The strains were analysed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The analysis of electrophoretic protein pattern of these bacteria supported the results of conventional testing, confirmed the distinction between the biovars "a" and "b" of Group EF-4 and supported the division of biovar EF-4b into two subgroups of either producing or non-producing acid from gluconate.