Members of the genus Aspergillus are among the filamentous fungal agents frequently causing infections in humans. A. fumigatus is the most commonly isolated fungal pathogen within the genus; however, other species, including A. terreus, A. flavus and A. niger are also of increasing importance. Infections caused by black aspergilli are especially frequent in developing countries with hot, humid, tropical or semitropical climates. Several reports revealed A. niger as the most common causative agent of otomycosis and fungal keratitis in certain geographic regions.
Species related to A. niger are difficult to identify on the basis of morphological criteria alone. Recent molecular analyses revealed that apart from A. niger, other black aspergilli, including A. tubingensis and the recently described species A. brasiliensis are also potential causative agents of human infections. In the case of corneal infections, the available data indicate that these species may be responsible for a significant proportion of cases caused by black aspergilli.
The aim of this review is to summarize the literature data about the involvement of black aspergilli (members of Aspergillus section Nigri) in human infections under tropical and semitropical climates, including otomycosis and eye infections. Available retrospective studies are summarized with special emphasis on the clinical manifestation, epidemiological aspects and therapeutical possibilities; furthermore, the molecular methods for the exact diagnosis and identification of black Aspergillus strains are also discussed.