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New Histoplasma-like fungus causing disseminated infection in AIDS

October 17 2013

In this week’s New England Journal of medicine, Chris Kenyon and colleagues describe disseminated infections in HIV infected patients with CD4 counts <50 caused by a dimorphic fungus, not recognised before. The fungus was cultured from skin and blood, but not sputum of CSF. Its yeast morphology was similar to that of Histoplasma capsulatum, on agar and in tissue, although the mycelial phase is distinctive. Cases have only been recognised since 2009, but probably have been occurring for longer.

The clinical features included fever, loss of weight, anaemia, skin lesions and a chest Xray similar to that seen in tuberculosis. Night sweats, hepatosplenomegaly and lymphadenopathy were less common. Patients were treated with a variety of antifungal agents but dramatic response was seen to IV amphotericin B (1mg/Kg) followed by itraconazole. Three patients died, early after presentation.

Molecular identification using ITS1 and 2 sequencing shows that the 13 isolates tightly clustered and are most similar to Emmonsia pasteuriana and E. parva, and slightly more distantly related to Histoplasma capsulatum. In an accompanying editorial by Jean Paul Latgé, he suggested a rodent source for this fungus, although there are no reports of its environmental isolation yet.

Links: Article by Kenyon NEJM  Kenyon appendix   NEJM Editorial  by Latge