Corynebacterium pseudotuberculosis (formerly known as C. ovis) is a well-known pathogen in sheep and goats, causing caseous lymphadenitis. This organism can also contain the phage-borne gene for the diphtheria toxin. Cases of lymphadenitis, purulent abscesses, and pneumonia have been reported primarily due to occupational exposure to sheep, but a pediatric case of necrotic lymphadenitis was also reported due to exposure to sheep while on vacation.
Corynebacterium pseudotuberculosis is similar to C. diphtheriae biotype gravis in that it can produce irregular rods with some club-shaped forms and can produce metachromatic granules.
This isolate will grow well on blood agar, is generally cream to white, and may appear with a matte surface and a small beta-hemolytic zone. Reverse CAMP is positive, and also like Corynebacterium diphtheriae, it can produce blackish colonies in the presence of tellurite (Tinsdale agar) due to the production of H2S. This isolate ferments glucose, fructose, galactose, maltose, mannose, and galactose and is urease and methyl red positive.
