Colonies (SDA) are white, flat, powdery, sometimes downy to fluffy with a brilliant lemon yellow reverse. Numerous large clavate microconidia are borne on the sides of hyphae. Macroconidia are smooth-walled, two- to six-celled, clavate, variable in size, and may have terminal appendages. Macroconidia are much shorter than those seen in T. mentagrophytes. RG-2 organism.
Culture of. T. erinacei showing its typical brilliant lemon yellow reverse pigment..
Microconidia and macroconidia of T. erinacei .
Kaminski's Dermatophyte Identification Scheme:
Littman Oxgall Agar (Difco): White, downy colony with yellowish green diffusible pigment.
Lactritmel Agar (Mycopathologia 91:57-59, 1985): White suede to powdery colony with brilliant yellow reverse. Numerous large slender clavate microconidia.
Sabouraud's Dextrose Agar with 5% NaCl: White folded suede to powdery colony with no reverse pigment.
1% Peptone Agar: White suede to powdery colony with pale yellow reverse.
Trichophyton Agar No. l: Good growth indicating no special nutritional requirements. Colonies are white suede to powdery with no reverse pigment.
Hydrolysis of Urea: Negative at 7 days
Vitamin Free agar (Difco Trichophyton Agar No.1): Good growth indicating no special nutritional requirements. Cultures are white, folded, suede-like to powdery with no reverse pigment.
Hair Perforation Test ("in vitro"): Positive
T. erinacei is generally distinguished from other varieties of T. mentagrophytes by (a) its microscopic morphology showing numerous large slender clavate microconidia borne on the slides of hyphae and its smooth, thin-walled clavate macroconidia; (b) its brilliant lemon yellow reverse pigment on plain Sabouraud's agar and Lactritmel agar; (c) its lack of reverse pigment on Sabouraud's salt agar; and (d) its negative hydrolysis of urea.
Trichophyton erinacei is a zoophilic fungus associated with hedgehogs and the epidermal mites which they often harbour. Human infections occur most frequently on the exposed parts of the body; but tinea of the scalp and nails can also occur. Invaded hairs show an ectothrix infection but do not fluoresce under Wood's ultra-violet light. The distribution of this fungus is New Zealand and Europe.
Rebell, G., and D. Taplin. 1970. The Dermatophytes. 2nd. revised edition. University of Miami Press, Coral Gables, Florida. USA.
Rippon, J.W. 1988. Medical Mycology. 3rd Edition. W.B. Saunders Co., Philadelphia, USA.