Harrison's Internal Medicine Chapter 131. Diphtheria and Other Infections Caused by Corynebacteria and Related Species Diphtheria Diphtheria is a nasopharyngeal and skin infection caused by Corynebacterium diphtheriae. Toxigenic strains of C. diphtheriae produce a protein toxin that causes systemic toxicity, myocarditis, and polyneuropathy. The toxin is associated with the formation of pseudomembranes in the pharynx during respiratory diphtheria. While toxigenic strains most frequently cause pharyngeal diphtheria, nontoxigenic strains commonly cause cutaneous disease. In the United States and Europe, diphtheria has been controlled in recent years with effective vaccination, although sporadic outbreaks have occurred. .
