Poster 01: Cutaneous diphtheria causing diabetic foot ulcer infection: A case report

Boyle LD; Amin A; Todd G; Kong WM
London North West University Healthcare NHS Trust

Background:
Cutaneous diphtheria is rare in England due to the success of the routine immunisation programme. Here we describe a unusual case of diabetic wound infection with toxigenic Corynebacterium ulcerans.

Case report:
A 62 year old male was referred to the acute multidisciplinary diabetes foot clinic. He had a history of type 2 diabetes complicated by retinopathy and neuropathy (contemporary HbA1c 63 mmol/mol). Following minor trauma, he had developed a left hallux ulcer with indurated edges, clinically infected with localised cellulitis over the dorsum. He remained systemically well. Pedal pulses were intact aside from a monophasic left posterior tibial. Bloods revealed WCC 12.9 and CRP 17.2. X-rays demonstrated bone resorption and destruction of the distal phalanx of the left hallux, due to active osteomyelitis. Ulcer tissue culture showed growth of Staphylococcus aureus, Group A Streptococcus, and a toxigenic strain (diphtheria toxin) of Corynebacterium ulcerans. Nose and throat swabs at the regional infectious diseases unit were negative. Interestingly he had visited Barcelona shortly before presentation, and kept pet dogs – one of which was also positive for toxigenic C. ulcerans on swabbing. Despite 6 weeks of oral co-amoxiclav and clarithromycin, wound healing was slow with ongoing infection. Serial podiatry tissue culture revealed heavy growths of C. ulcerans; Public Health England recommended both the patient and household contacts receive further treatment with oral erythromycin, but not diphtheria anti-toxin.

Conclusion:
Early manifestations of cutaneous diphtheria can appear as non-healing well-demarcated diabetic foot ulcers. Careful history taking including foreign travel and companion animals is essential.