بويغاء كلبية

Microsporum canis is distinguished from other dermatophytes within this genus by a hair perforation test. Microsporum canis shows a positive hair perforation test telling the observer that this type of dermatophyte grows into the hair shaft causing brittle breakable hairs. Another less sensitive test that can be used to diagnose Microsporum canis is the use of a Wood’s lamp, a fancy name for a certain wavelength of blacklight. Under the Wood’s lamp, Microsporum canis will fluoresce green, but only approximately 50% of the Microsporum canis strains will show fluorescence (1). After observation of either a positive hair perforation test or a positive Wood’s lamp test, the observer should then macroscopically and microscopically be able to distinguish this species from others due to the characteristcs mentioned in the description of the species above.

Microsporum canis is a dermatophyte found world wide causing tinea capitis and tinea corporis in humans. Microsporum canis has the ability to infect the keratinzed tissues such as the skin, hair and nails because of the virulent factor, keratinase(2). This species is zoophilic and the natural reservoir for Microsporum canis is dogs and cats, but can be equally virulent to humans, especially children. Humans generally contract ringworm through direct contact with an infected animal. To be sure this does not happen to you or your children, make sure your household pets, such as cats and dogs have been checked and treated for ringworm. If infected with Microsporum canis, griseofulvin is a drug that can be used, but less expensive and safer drugs have been developed such as oral terbinafine and intraconazole (1).

Microsporum canis, macroscopically, is a white to yellowish colony with a velvety/powdery texture approximately 3 to 9 cm in diameter. When the petri plate is flipped upside down, the colony ranges from being burnt orange to yellow depending on what strain of Microsporum canis may be growing on the plate(1).

Microsporum canis, microscopically, produces septate hyphae along with both macroconidia and microcondia. The Macroconidia are fusiform spindle-shaped approximately 35-125 X 7-20 micrometers in size. The macroconidia have thin septate walls within them with approximately 6-15 cells (1). The macroconidia’s outer walls tend to be very thick and rough. The microconidia also produced by this species are clavate and 4-7 X 2.5-3.5 micrometers in size (1).

As mentioned earlier, Microsporum canis can be found world wide infecting domestic cats and dogs, wild cats and dogs, humans and less commonly monkeys, horses, and rabbits. The only soil reported findings have been reported from sand beaches in Hawaii and soil in Romania (2).

Other taxa that may look similiar to Microsporum canis are other dermatophytes such as the genera Epidermophyton and Trichophyton. Although Microsporum species can be distinguished from these other two genera by having spindle-shaped macroconidia with rough enchinulate walls(3).

Microsporum canis is mostly a dermatophyte and can only be used by people for research as well as new and improved drug treatments. Although, maybe not Microsporum canis the species itself, but other dermatophytes are used by South American and African tribes as a sign of beauty. Some of the dermatophytes form geometrical shapes on the skin, which is known to be aesthetically pleasing in these tribes.