'Corynebacterium ulcerans': a potential cause of diphtheria.

Symptoms similar to those of diphtheria may occasionally be caused by micro-organisms other than Corynebacterium diphtheriae, such as zoonotic corynebacteria. A case of pharyngitis caused by toxigenic 'C. ulcerans' in a 9 year old girl illustrates the importance of including diphtheroids in the differential diagnosis. The presenting symptoms may have been attenuated by previous immunisation against C. diphtheriae. 'C. ulcerans' should be considered in the differential diagnosis of pharyngitis, especially in patients with a history of contact with farm animals or the consumption of raw dairy products.