PORPHYROMONAS-LIKE GRAM-NEGATIVE RODS IN NATURALLY-OCCURRING PERIODONTITIS IN DOGS

A total of 259 Gram-negative Porphyromonas-like rods isolated from sub gingival plaque samples of 16 family-owned dogs with naturally occurri ng periodontitis were characterized phenotypically by biochemical reac tions, metabolic end products and enzymatic activities (API-ZYM(TM), R osco(TM)). Four distinct groups were found. Group A isolates (63) were asaccharolytic, lipase negative, trypsin positive and produced phenyl acetic acid (PAA) from peptone-yeast extract glucose broth. Unlike P. gingivalis strains they were catalase positive. Group B isolates (42) differed from those of group A by a positive lipase reaction and from those of group D by failing to ferment sugars. Group C isolates (88) w ere asaccharolytic and did not produce PAA. They were alpha-fucosidase , N-acetyl-beta-glucosaminidase (beta-NAG) and trypsin negative, resem bling P. endodontalis, but unlike human isolates, they were catalase p ositive. Subgroup C.1 isolates (6) differed from those of parent group C by producing minor amounts of PAA, and subgroup C.2 isolates (12) w ere beta-NAG positive. Group D isolates (46) were weakly fermentative, lipase, catalase and trypsin positive, and produced PAA. They resembl ed the B. (P.) salivosus type strain which, in our hands, fermented we akly glucose, lactose and mannose. Two isolates could not be assigned to any of the previous groups.