Question

This is a question for medical microbiology

A male patient is admitted to the emergency room in a weakened state with a persistent fever and weight loss. His history includes the fact that he is HIV-positive and, until recently, lived in Panama. Blood work demonstrates reduced white cell, platelet, and red cell numbers. Bone marrow examination reveals a decreased number of white cells and the presence of an ascomycete yeast. The yeast produces numerous macroconidia when cultured on an agar plate.

What is wrong with this patient? Explain your reasoning.

Is there an environmental source would you associate this organism?

Answer 1

Answer: The patient could be infected with Histoplasma capsulatum which causes histoplasmosis. In immunocompromised individuals such as the HIV positive patients, this infection can become systemic and lead to further complications. The pathogenesis includes proliferation in macrophages which aids the dissemination of the organism within the spleen, liver, bone marrow, and lymph nodes. This also leads to thrombocytopenia (Loss of platelets), pancytopenia (loss of all blood cells), and coagulopathy. This organism shows yeast like budding in the human system, while in the external environment it occurs in the mould form and forms microconidia as well as macroconidia.

Histoplasma capsulatum is found in large numbers in the nitrogen rich soil and infection happens due to inhalation of the microconidia or hyphal elements.