Nondermatophytic filamentous keratinophilic fungi and their role in
Harish C. Gugnani
Department of Medical Mycology, Vallabhbhai Patel Chest Institute, University
of Delhi, India
Keratinophilic fungi include a variety of filamentous fungi mainly comprising
hyphomycetes and several other taxonomic groups. Hyphomycetes include dermatophytes
and a great variety of nondermatophytic filamentous fungi. Most of the
latter occur as saprophytes in soil, and some are plant pathogens. Chrysosporium
species are the commonest nondermatophytic filamentous fungi and are predominantly
recovered from soil and other natural substrata by hair-baiting technique.
C. tropicum and C. pannicola have been frequently isolated from human and
animal skin lesions but their etiological relationship has not been established.
Nattrassia mangiferae, a coelomycete with its anamorph as Scytalidium dimidiatum,
is a well known plant pathogen, and has been frequently reported during
the last three decades as an etiological agent of human skin and nail infections.
Another species of Scytalidium, viz. S. hyalinum, regarded as an albino
mutant of S. dimidiatum has also been frequently known to cause similar
infections. Phoma, another coelomycete, includes several species pathogenic
to humans. Among other nondermatophytic filamentous keratinophilic fungi
known to cause human infections are species of Fusarium, Scopulariopsis,
Aspergillus, Geotrichum, Alternaria, Curvularia, Onychocola, Microascus,
Aphanoascus and Chaetomium. Several species of gymnoascaceous fungi, viz.
Ctenomyces serratus, Gymnoascus reesii, G. intermedius and Gymnascella
dankaliensis are often isolated from soil by hair-baiting technique; they
have also been occasionally recovered from human skin lesions but without
any evidence of etiological relationship. The criteria considered important
for evaluating the role of nondermatophytic filamentous fungi in skin infections
are the demonstration of mycelial elements in direct microscopy of skin
scrapings or biopsy compatible with those in culture, repeated positive
cultures from clinical material, and the exclusion of infection due to
a dermatophyte or a fungus other than the one in question.
In: Kushwaha RKS, Guarro J (Eds.). Biology
of Dermatophytes and other Keratinophilic Fungi.
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Revista Iberoamericana de Micología, Bilbao, 2000.