A Rare Case of Locally Contracted Cutaneous Corynebacterium diphtheriae

A 32-year-old man with a history of intravenous heroin use and housing instability presented with three years of worsening left forearm and wrist "infection," which had progressed over the past few months with worsening purulence, pain, and deformity. In the emergency department, he was afebrile with stable vitals. Superficial cultures drawn demonstrated polymicrobial growth, including heavy growth of Corynebacterium diphtheriae. He was treated with vancomycin and then IV penicillin to complete 10 days of therapy. Given the uncharacteristic appearance of the lesion, a biopsy was recommended, but the patient left against medical advice. Later, the diphtheria isolate was identified as C. diphtheriae var. mitis by the Centers for Disease Control and Prevention (CDC). This describes an atypical case of cutaneous diphtheria, a disease that is infrequently seen in the United States due to the high prevalence of routine vaccination.