Diphtheria By Larry M Bush, MD, FACP, Charles E Schmidt College of Medicine, Florida Atlantic University; Maria T Vazquez-Pertejo, MD, FACP, Wellington Regional Medical Center Reviewed / Revised Mar 2023 View Patient Education Symptoms and Signs Diagnosis Treatment Prevention Key Points More Information Topic Resources Diphtheria (Nasopharyngeal... Diphtheria (Nasopharyngeal... Diphtheria (Cutaneous) Cutaneous Diphtheria (Central... Diphtheria is an acute pharyngeal or cutaneous infection caused mainly by toxigenic strains of the gram-positive bacillus Corynebacterium diphtheriae and rarely by other, less common Corynebacterium species.