Anti-interferon-gamma autoantibody-associated immunodeficiency may explain severe melioidosis and necrotic skin lesionsNew immune condition may explain severe cases of melioidosis infection

Melioidosis, caused by the environmental saprophyte Burkholderia pseudomallei, is acquired from soil and surface water and rises sharply in incidence after heavy rainfall and flooding—something that extreme-weather trends under climate change are expected to make more frequent and more widespread. The disease presents with a broad clinical spectrum, but eschars or ecthyma gangrenosum-like necrotic skin lesions are very rarely reported and may be mistaken for scrub typhus in coendemic regions. A 66-year-old woman from northeast Thailand with no known comorbidity presented with fever and chest pain 1 week after walking barefoot through floodwater. Contrast-enhanced computed tomography demonstrated mediastinal necrotic lymphadenitis and hepatosplenic microabscesses. Despite broad-spectrum β-lactam therapy, she remained febrile and, on illness day 8, developed a painful subcutaneous nodule that evolved within 2 days into a dark, eschar-like lesion. Pus culture grew B. pseudomallei that was resistant to ceftazidime and susceptible to imipenem and trimethoprim/sulfamethoxazole. Her fever and skin lesion resolved with meropenem. Because the disease was unusually aggressive and accompanied by recurrent, self-limiting panniculitis-like episodes, she was evaluated for adult-onset immunodeficiency and anti-interferon-γ autoantibodies were detected. She completed 1 month of meropenem followed by trimethoprim/sulfamethoxazole eradication therapy, and imaging at 3 months showed complete resolution. A structured review identified only six previously published patients with an eschar or eschar-like necrotic lesion in culture-confirmed melioidosis; the majority, as in our patient, had disseminated disease, and almost all had a documented soil or freshwater exposure. Melioidosis should be considered in patients with rapidly progressive visceral abscesses and necrotic skin lesions in the weeks after flooding or other heavy freshwater exposure in endemic regions, and unexplained severity should prompt evaluation for anti-interferon-γ autoantibody-associated immunodeficiency together with confirmation of unusual resistance phenotypes. As flooding becomes more frequent, clinical awareness and simple protective measures during and after floods are likely to be increasingly important.