C. diphtheriae can be biochemically differentiated from C. pseudotuberculosis by

-C. pseudotuberculosis is urease positive and is thus differentiated from C. diphtheriae. - C. pseudotuberculosis causes caseous lymphadenitis in sheep and goats. Corynebacterium - catalase positive. Oxidase positive organisms are: Pseudomonas aeruginosa Burkholderia species Vibrio Pasteurella multocida Brucella Neisseria Haemophilus spp Campylobacter Potassium tellurite agar (PTA) is the selective media used for C. diphtheriae.