Corynebacterium spp are a small, generally nonmotile, Gram-positive commensal bacteria of the dog skin, reproductive tract and gastrointestinal tract. Corynebacteria are aerobic or facultatively anaerobic and they exhibit a fermentative metabolism (carbohydrates to lactic acid) under certain conditions. Species which are pathogenic to dogs include: 1  Corynebacterium pyogenes (purulent infections). 2  Corynebacterium auriscanis. 3  Corynebacterium epidermidicanis. 4  Corynebacterium urealyticum (cystitis). 5  Corynebacterium ulcerans (zoonotic reservoir for human diphtheria).