ABSTRACT
Numerous darkly pigmented fungi are causal agents of human and animal diseases. These pathogens are a diverse group of hyphal or pseudohyphal fungi that have brown-colored cell walls due to the presence of melanin. The hyphae are septate and branched. Some of these fungi also have yeast-like cells. They also produce numerous kinds of darkly-colored spores. Such fungi are designated as being melanized or dematiaceous (Etymology; Gk., “deme” meaning “bundle”). The term dematiaceous is a misnomer but is fi rmly entrenched in mycological and clinical usage to indicate brown-colored fungi (Revankar and Sutton, 2010). The melanin production may vary with conditions of growth of the fungus and among different fungi. In fact, it has been demonstrated in almost all the so-called non-dematiaceous hyaline-looking clinical fungi also such as Candida albicans, Histoplasma capsulatum, and others (Revankar and Sutton, 2010). Melanin is a polyphenolic compound and is present in many microbes and other groups of organisms. It can be histochemically demonstrated using the Masson-Fontana stain. It is extremely stable and resistant to many destructive processes (Revankar and Sutton, 2010). Melanin is thought to play an important role in evading host defenses (Walsh et al., 2004) and in survival of the pathogen in harsh environments. It also helps protect these fungi from macrophages, neutrophils and from antifungal agents (Santos et al., 2013).
