Trichophyton Mold SpeciesTrichophyton species are causative agents of Dermatophytosis, Onychomycosis, Tinea barbae, Tinea capitis, Tinea corporis, Tinea cruris, Tinea faciei, and Tinea pedis. (Information from www.doctorfungus.org @ 2005)
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Taxonomic Classifications Kingdom: FungiPhylum: AscomycotaClass: EuascomycetesOrder: OnygenalesFamily: ArthrodermataceaeGenus: Trichophyton
Trichophyton Mold Pictures
(Image Courtesy of www.doctorfungus.org @ 2005)
Microscopic morphology of a Trichophyton species showing relatively broad hyphae, irregular and much branched with numerous septa. |
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Ecology Trichophyton is a dermatophyte fungus which is primarily isolated from the soil, humans, or animals. The genus includes anthropophilic, geophilic, and zoophilic species. Certain Trichophyton species are cosmopolitan while others have a limited geographic distribution. Trichophyton species that is endemic at Central America, Pacific Islands and Southeast Asia is T. concentricum.
Species There are twenty – two species under genus Trichophyton. Most common are Trichophyton concentricum, Trichophyton mentagrophytes, Trichophyton rubrum, Trichophyton schoenleinii, Trichophyton tonsurans, Trichophyton verrucosum, and Trichophyton violaceum. Out of the total number of species, eleven are commonly associated with tinea of the scalp, the nails, and the skin in humans while only four are often isolated from animals.
Table 1. Natural Habitats of Trichophyton Species
Pathogenicity and Health Effects Trichophyton is a keratinophilic filamentous fungus which has the ability to invade keratinized tissues thus; it is considered as one of the leading causes of hair, skin, and nail infections in humans. Possession of several enzymes, such as acid proteinases, elastase, keratinases, and other proteinases are the major virulence factors of Trichophyton species.
Out of the total number of species, eleven are commonly associated with tinea of the scalp, the nails, and the skin in humans while only four are often isolated from animals. Additionally, Trichophyton species may cause invasive infections in immunocompromised patients. Trichophyton rubrum is the commonest causative agent of dermatophytoses worldwide.
Most of the Trichophyton species have teleomorphic forms and these teleomorphs are classified under genus Arthroderma.
Macroscopic Appearance Ø Growth rate may range from being slow to moderately rapid, and colonies are waxy, glabrous, downy to cottony; and Ø Surface colony color ranges from white to bright yellowish beige or red violet and the reverse may be pale, yellowish, brown, or red – brown.
Microscopic Appearance Ø Hyaline, septate hyphae, microconidia, macroconidia, and conidiophores, and arthroconidia are present, chlamydospores may also be produced; Ø Conidiophores are little differentiated from vegetative hyphae; Ø Microconidia are unicellular, round - to pyriform – shaped, numerously present, may be solitary or arranged in grape – like clusters; Ø Macroconidia are multicellular (with two or more cells), may either be smooth -, thin -, or thick – walled, cylindrical, club – shaped, or cigar – shaped, and are often absent; and Ø Several species are typically sterile; however, sporulation may be induced with the use of an appropriate media.
Laboratory Precautions General laboratory precautions are required, no special safety measures needed.
Susceptibility Generally, amorolfine, clotrimazole, itraconazole, ketoconazole, naftifine, and terbinafine are general active in vitro against Trichophyton species. Terbinafine usually shows to be the most effective agent. Isolates of Trichophyton rubrum are more vulnerable to antifungal agents compared to Trichophyton mentagrophytes. Also active in vitro against Trichophyton species are the azole derivatives, Syn 2869, Syn2836, Syn2903, and Syn2921.
Terbinafine and itraconazole are commonly used now in treatment of infections caused by Trichophyton species compared to griseofulvin which is once the drug of choice for dermatophytosis treatment; however, due to the availability of more effective and less toxic drugs griseofulvin is now less commonly used. Oral therapy is usually preferred for treatment of tinea capitis and onychomycosis.
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The mycological information gathered and
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