Share The characteristic pseudomembrane is classically seen in diphtheria. The horse in the case study had a similar lesion. Photo: User: Dileepunnikri, CC BY-SA 3.0 via Wikimedia Commons The case of a diphtheria-like infection confirmed in a gelding in Britain indicates a role for horses as reservoirs for the bacterium Corynebacterium ulcerans, which can infect a range of species. Diphtheria and diphtheria-like infections are caused by three Corynebacterium species, Corynebacterium diphtheriae, Corynebacterium pseudotuberculosis. While C. ulcerans and Nevertheless, both have infected people, with clinical signs indistinguishable from those caused by C. diphtheriae being increasingly reported. Flavia Zendri and her fellow researchers, in a case report published in the journal