曾用名：石膏样毛癣菌（T.gypseum）、须癣小孢霉（M.mentagrophytes）、颗粒状毛癣菌（T.granulosum）、反射状毛癣菌（T.radiolatum）、星状毛癣菌（T.asteroides）、趾间毛癣菌(T.interdigitale)、K-W毛癣菌（T.koufmann-wolf）

培养基上：在SDA上迅速、白色、黄色或淡红色，粉末状、圆盘状，扁平或圆盘状等6种类型刚，菌落中心部有结节状小隆起，有时呈不规则、较大的放射状沟纹，或呈白色绒毛状菌落，仅在边缘附近有黄色粉末，背面呈淡黄色、棕色、棕红或淡红色，根据菌落形态分六个型。

镜下：棒状或腊肠庄大分生孢子，有2-8个分隔，分隔处可见变窄；细胞壁薄，小分生孢子多见，有时呈葡萄串状。可见螺旋状菌丝、结节状器官、破梳状菌丝。大分生孢子在粉末状菌落中较多见，在绒毛状菌落中较少见或无。经KOH处理后，可见分隔菌丝，毛发上为发外孢子，孢子较大，排列成串，包围发干。

• 石膏样小孢子菌的菌落色素较深，呈棕黄色，背面红色，大分生孢子呈纺锤形，有4-6个分隔
• 马类毛癣菌的菌落中央开裂，典型菌落边缘有一圈黄色素，生长需要烟酸。

Trichophyton mentagrophytes

On Sabouraud's dextrose agar, colonies are generally flat, white to cream in colour, with a powdery to granular surface. Some cultures show central folding or develop raised central tufts or pleomorphic suede-like to downy areas. Reverse pigmentation is usually a yellow-brown to reddish-brown colour. Numerous single-celled microconidia are formed, often in dense clusters. Microconidia are hyaline, smooth-walled, and are predominantly spherical to subspherical in shape, however occasional clavate to pyriform forms may occur. Varying numbers of spherical chlamydoconidia, spiral hyphae and smooth, thin-walled, clavate shaped, multicelled macroconidia may also be present.

Kaminski's Dermatophyte Identification Scheme:

Littman Oxgall Agar (Difco): Raised greyish-white, suede-like to downy colony. Some cultures may show a diffusible yellow to brown pigment.

Lactritmel Agar (Mycopathologia 91:57-59, 1985): Cultures are flat, white to cream in colour, with a powdery to granular surface. Some cultures develop raised central tuft or pleomorphic downy areas. Reverse pigmentation is yellow-brown to pinkish-brown to red-brown. Microscopic morphology similar to that described above, with predominantly spherical microconidia, often forming in dense clusters, and varying numbers of spherical chlamydoconidia, spiral hyphae and smooth, thin-walled, clavate, multiseptate macroconidia.

Sabouraud's Dextrose Agar with 5% NaCl: Cultures are heaped and folded, buff to brown in colour, with a suede-like surface texture and characteristically have a very dark reddish-brown submerged peripheral fringe and reverse pigmentation.

1% Peptone Agar: Flat, cream coloured, powdery to granular colonies with no reverse pigment.

Hydrolysis of Urea: Positive within 7 days (usually 3 to 5 days).

Vitamin Free agar (Difco Trichophyton Agar No.1): Good growth indicating no special nutritional requirements. Cultures are flat, cream coloured, with a powdery to suede-like surface, and have a reddish-brown reverse pigmentation.

Hair Perforation Test ("in vitro"): Positive within 14 days.

T. mentagrophytes, (granular variety or zoophilic form are not acceptable varietal names) can be distinguished from other T. intergigitale by (a) its granular appearance on the 1% Peptone agar, (b) it's microscopic morphology of more spherical microconidia and generally greater numbers of macroconidia and (c) a yellow to brown diffusible pigment is often seen on the Littman Oxgall agar.

Clinical significance:

T. mentagrophytes is the zoophilic form of T. mentagrophytes with a world-wide distribution and a wide range of animal hosts including mice, guinea-pigs, kangaroos, cats, horses, sheep and rabbits. Produces inflammatory skin or scalp lesions in humans, particularly in rural workers. Kerion of the scalp and beard may occur. Invaded hairs show an ectothrix infection but do not fluoresce under Wood's ultra-violet light.

Mycosis: Dermatophytosis

Further reading:

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.

Trichophyton | Mycology Online