Many yeasts and molds can cause opportunistic, even life-threatening infections in immunocompromised patients. These infections only rarely affect immunocompetent people. Yeasts tend to cause fungemia as well as focal involvement of skin and other sites.
(See also Overview of Fungal Infections.)
Blastoschizomyces capitatus and Trichosporon species (including T. ovoides, T. inkin, T. asahii, T. mucoides, T. asteroides, and T. cutaneum) are yeasts that cause often fatal disseminated infection, particularly in neutropenic patients. Among Trichosporon, T. asahii is the most common cause of disseminated disease. The name T. beigelii, now obsolete, was formerly used for all or any of these Trichosporon species.
Malassezia furfur fungemia typically affects infants and debilitated adults receiving lipid-containing IV hyperalimentation infusions.
Talaromyces marneffei (formerly called Penicillium marneffei) is an opportunistic invader in Southeast Asian patients with AIDS, and cases have been recognized in travelers returning to the US after visiting that region. T. marneffei skin lesions may resemble molluscum contagiosum.
Especially in neutropenic patients, various environmental molds, including species of Fusarium and Scedosporium apiospermum, both of which are becoming more frequent, can cause focal angioinvasive vasculitic lesions mimicking invasive aspergillosis. Fusarium species cause superficial infections (eg, keratitis, onychomycosis) in immunocompetent patients and disseminated infections in severely immunocompromised patients with prolonged, severe neutropenia and/or severe T-cell immunodeficiency. Fusarium species (unlike Aspergilli) may grow in routine blood cultures from patients with disseminated infection. Voriconazole is considered the drug of choice for both Fusarium and S. apiospermum.
Specific diagnosis requires culture and species identification and is crucial because not all of these organisms respond to any single antifungal drug. For example, Scedosporium species are typically resistant to amphotericin B. Optimal regimens of antifungal therapy for each member of this group of fungal opportunists must be defined.