Amphotericin B Resistant Filamentous Fungi: Fusarium, Pseudoallescheria, and Other Tenacious Moulds



Aspergillus fumigatus is the most common filamentous fungus causing invasive mycoses of the respiratory tract in immunocompromised hosts. Amphotericin B is active in vitro and in vivo against A. fumigatus and is a standard of care in treatment of infections riot to this organism. However, other filamentous fungi, including Fusarium spp., Pseudallescheria boydii (Scedosporium apiospermum), and Aspergillus terreus may be resistant to safely achievable concentrations and dosages of amphotericin B. Current in vitro and in vivo studies indicate that some antifungal triazoles may be active alone and in combination with amphotericin B, depending upon the species. The triazoles itraconazole, voriconazole, posaconazole, and ravuconazole may show in vitro and in vivo activity against some or all of these pathogens. These polyene-resistant filamentous fungi may cause patterns of infection, including sinusitis, pneumonia, and disseminated infection that are similar to those of A. fumigatus. Certain clinical features, such as fungemia due to a mould, may be a harbinger to a subsequent microbiological diagnosis of Fusarium spp. However, most infections due to these organisms are indistinguishable from those due to A. fumigatus. Hence, a microbiological diagnosis is important, albeit not always achievable, in lieu of empirical therapy for suspected filamentous fungal infections, such as pneumonia and sinusitis, in immunocompromised hosts. Ongoing studies of the pathogenesis, molecular detection, in vitro susceptibility, in vivo therapeutics, and clinical trials involving these organisms may help to guide rational decisions in management of polyene-resistant mycoses.

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IDSA 38th
    • IDSA 38th