[Actinomyces pyogenes: conventional and Api system bacteriologic study of 103 strains isolated from ruminants]

One hundred and three strains of Actinomyces pyogenes isolated from ruminants were examined for morphological, cultural and biochemical properties by standard tests and by the Api 50 CH and Api Coryne methods. No biotype could be demonstrated, but a few atypical non- or practically non-proteolytic strains were detected which should be differentiated from Arcanobacterium haemolyticum. Criteria for laboratory identification of A pyogenes were established: Gram stain; culture on blood agar; deep agar and Loeffler's medium; catalase, nitrate reduction, acid formation from xylose; Hugh and Leifson test. The Api Coryne system correctly identified only 58 of 103 A pyogenes cultures, which implies that it should be re-evaluated before use in veterinary diagnosis laboratories.