Factors affecting growth and urease production by Trichophyton spp.

Abstract

Among Trichophyton spp. examined for urease production, T. rubrum was negative, whereas T. mentagrophytes appeared to be the most active species. Urease was not detected in cell-free culture fluids of the tested fungi. The endocellular urease of the test fungi was essentially constitutive. Moreover, addition of urea to the growth medium of these organisms markedly inhibited their mycelial biomass and ureolytic yield. Environmental factors showed variable effects on the test fungi and there was no correlation between mycelial growth and urease activity of these fungi.

Closely related dermatophyte species produce different patterns of secreted proteins

“…On the basis of their primary habitat, dermatophytes are classified as anthropophilic (humans), zoophilic (animals) or geophilic (soil) (Weitzman & Summerbell, 1995;Weitzman & Padhye, 1996). In addition, isolates of Trichophyton rubrum and of the anthropophilic variety of Arthroderma vanbreuseghemii (Trichophyton interdigitale) (Gräser et al, 1999) sometimes show the same morphology when grown on Sabouraud's medium, thus leading to their misidentification (Kane & Fischer, 1971;Mahmoud et al, 1996). Some zoophilic and geophilic dermatophyte species like Trichophyton verrucosum and Microsporum gypseum can infect humans (Lateur, 2000;Khosravi & Mahmoudi, 2003).…”

“…The zoophilic species Trichophyton equinum and the anthropophilic species Trichophyton tonsurans possess almost identical internal transcribed spacer (ITS) regions and ribosomal DNA sequences (Gräser et al, 1999;Summerbell et al, 1999). In addition, isolates of Trichophyton rubrum and of the anthropophilic variety of Arthroderma vanbreuseghemii (Trichophyton interdigitale) (Gräser et al, 1999) sometimes show the same morphology when grown on Sabouraud's medium, thus leading to their misidentification (Kane & Fischer, 1971;Mahmoud et al, 1996). Moreover, the inflammatory reactions produced by dermatophytes in the host have been shown to vary from mild to severe according to the primary habitat of the fungus, the anatomic location of the infection and the host's reactions to the metabolites secreted by the fungus (Wagner & Sohnle, 1995;Nissen et al, 1998;Mari et al, 2003).…”

Comparative analysis of secreted enzymes between the anthropophilic–zoophilic sister species Trichophyton tonsurans and Trichophyton equinum

“…These proteolytic and lipolytic enzymes facilitate nutrient acquisition (Apodaca & McKerrow 1989a, b) and, in live hosts, play a significant role in host specificity, immunogenicity and virulence Grappel & Blank 1972;Collins et al 1973;Wagner & Sohnle 1995;Mahmoud et al 1996;Nissen et al 1998;Mari et al 2003;Giddey et al 2007a). Given their importance in the pathogenesis of infections, an understanding of the differences in these genes at the structural and functional levels may help to elucidate how two, otherwise very closely related, organisms (e.g.…”