Dematiaceous fungi

Dematiaceous fungi are responsible for a wide variety of infectious syndromes. They are often found in soil and generally distributed worldwide. This suggests that most if not all individuals are exposed to them, presumably from inhalation or trauma. In recent years, these fungi have been increasingly recognised as important pathogens. The spectrum of diseases they are associated with has also broadened and includes superficial and deep local infections, allergic disease, pneumonia, brain abscess and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common aetiological agents. These fungi may have unique pathogenic mechanisms owing to the presence of melanin in their cell walls, which imparts the characteristic dark colour to their spores and hyphae. Diagnosis rests on careful microscopical and pathological examination, as there are no simple laboratory tests to reliably identify these fungi. Therapy depends upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Azoles such as itraconazole and voriconazole have the most consistent in vitro activity, though there is more clinical experience with itraconazole. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.