Medical Microbiology

Classification.Dermatophytesareclassifiedinthreegenera:Trichophyton

(withtheimportantspeciesT.mentagrophytes,T.rubrum,T.schoenleinii,

T.tonsurans);Microsporum(M.audouinii,M.canis,M.gypseum);andEpi-

dermophyton(E.floccosum).Somedermatophytespeciesareanthropophilic,

otherszoophilic.ThenaturalhabitatofthegeophilicspeciesM.gypseumis

thesoil.

Morphologyandculture.Thedermatophytesarefilamentousfungi.They

growreadilyonfungalnutrientmediumsat 25 – 308 C.After 5 – 14 days,cul-

tureswithawoollyappearance,indifferentcolors,usuallydevelop(Fig.6. 8 ).

Pathogenesisandclinicalpictures.Dermatomycosesareinfectionsthatare

transmitteddirectlybyhumancontact,animal-humancontactorindirectly

oninanimateobjects(clothes,carpets,moisture,anddustinshowers,swim-

mingpools,wardrobes,gyms).Thelocalizationoftheprimaryfocicorre-

spondstothecontactsite.Thusfeet,uncoveredskin(hair,head,facial

skin)areaffectedmostfrequently.Differentspeciescancausethesameclin-

icalpicture.Frequentdermatomycosesinclude:

CutaneousMycoses 373

Dermatophytes

a^50 μm

b^50 μm

Fig.6. 8 a Microsporum

canis. Lactophenolblue

preparation: large, fusi-

formmacroconidia.

bTrichophytonmentagro-

phytes.Lactophenolblue

preparation:thin-walled,

cylindricalmacroconidia;

numerous microconidia,

often in clumps; spiral

hyphae.

6

Kayser, Medical Microbiology © 2005 Thieme