“Did I Hear You Correctly? The Organism Identified Was Corynebacterium diphtheriae?”

Diphtheria is a bacterial infection caused by Corynebacterium diphtheriae and is primarily transmitted from person to person through close physical and respiratory contact; disease can involve almost any mucous membrane and is classified depending on the anatomic site of infection. Diphtheria is an acute, toxin-mediated disease whose occurrence is characterized by periodicity and epidemic waves, with a high incidence and mortality. Once one of the leading causes of childhood death, global diphtheria incidence declined approximately 70% through implementation of widespread vaccination programs. However, a major epidemic of diphtheria occurred during the 1990s in the Russian Federation and the newly independent states of the former Soviet Union. Although the epidemic is under control, toxigenic C. diphtheriae strains are still reported in Europe and globally, including North and South America, the Indian subcontinent, Africa, Southeast Asia, and the eastern Mediterranean. Rapid clinical and public health responses are required to control diphtheria outbreaks, with the clinical microbiology laboratory playing an essential role in providing prompt and rapid identification. In light of experience with a recent case of nontoxigenic C. diphtheriae respiratory infection, aspects of this organism and the diseases it causes are reviewed.