Expression of trypsin-like activity by the genera Corynebacterium and Actinomyces in canine periodontitis

Trypsin-like activity (TLA), clinical parameters and TLA-postitive bacteria mere examined in periodontitis and healthy sites in dogs. TLA was markedly higher in periodontitis than at healthy sites. There was good correlation between TLA positivity and severity of periodontal disease. The proportions of TLA-positive bacteria to total isolates in periodontitis and healthy si tes were 21.1% and 2.1%, respectively. Among TLA-positive bacteria in perio dontitis sites, 4.4% showed strong TLA activity, 35.3% showed moderate and 60.3% showed weak activity, In the healthy sites, all the TLA-positive bact eria showed weak activity. In all, 90% of the total number of TLA-positve b acteria were identified as belonging to the family Actinomycetaceae; 40% of bacteria belonging to the family Actinomycetaceae were identified as genus Corynebacterium with moderate trypsin-like activity and the remaining 60% were identified as genus Actinomyces with weak activity. Obligately anaerob ic bacteria accounted for only 5.9% of the total population of TLA-positive bacteria; they were gram-negative coccobacilli, gram-positve rods and gram -positive cocci, These observations suggested that bacteria in the family A ctinomycetaceae may play an important role in periodontitis and that measur ement of TLA is a clinically reliable marker for the diagnosis of periodont itis in dogs.