P025 More than a sore: cutaneous diphtheria in a returned traveller

Abstract

Cutaneous diphtheria is a rare condition in Europe, typically associated with travel to endemic regions, and may present diagnostic challenges due to its nonspecific clinical features. We report a case of cutaneous diphtheria in a young woman following travel to Sri Lanka, highlighting the importance of considering this diagnosis in returned travellers with persistent skin ulceration. A 27-year-old woman with a history of Raynaud disease, not on regular medications, presented with a nonhealing ulcer over the right lateral foot. While surfing on holiday in Sri Lanka 1 month prior to presentation, she recalled sustaining a minor abrasion to the right lateral foot, directly over a mosquito bite in the same location. She denied barefoot exposure to soil. The area became intensely pruritic and progressed from a pustule to a blister, which subsequently ruptured and ulcerated. During her return flight to Europe, she developed upper-respiratory-tract symptoms and subjective fevers, which resolved spontaneously within 3 days of arrival home. However, the foot lesion persisted. Clinical examination revealed a well-demarcated violaceous 20 × 20-mm circular ulcer on the mid right lateral foot. A 4-mm punch biopsy demonstrated focal ulceration with inflamed scale crust, epidermal hyperplasia and dermal mixed inflammation. Gram staining revealed possible Gram-positive coccobacilli, and tissue culture isolated Corynebacterium diphtheriae. Public health authorities were notified promptly. Initial treatment with azithromycin was commenced; however, antimicrobial susceptibility testing demonstrated resistance. Therapy was switched to oral linezolid, to complete a 14-day course, resulting in complete clinical resolution of the ulcer. A case of cutaneous diphtheria in the returning traveller highlights the importance of an accurate clinical history to ensure management is optimized. It is imperative for the correct microbiological diagnosis, as in this case, in conjunction with antimicrobial resistance testing.