Cutaneous Mycoses Dermatophytosis Lecture Four
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Transcript of Cutaneous Mycoses Dermatophytosis Lecture Four
Cutaneous Mycoses (dermatophytosis)
General futures Involves skin, nail, and hair Known as ringworm or tinea Keratinized layer are infected Fungi known as dermatophytes Infection range form mild to sever Depend on host state and fungal species Resist cycloheximide
Etiologic agents
Over hundred species described Only 40 are valid less associated with human diseases Grouping of dermatophytes Anamorphic state (asexual phase)Three genera Depend on sporulation
Etiologic agents cont.
Morphologic futuresNutritional requirementsMicrosporum, Trichophyton and
Epidermophyton
Natural habitat
Anthropophilic (humans) Zoophilic (animal) Geophilic (soil) All of them can cause diseases in human
Natural habitat Cont.
ANTROPOPHILIC Trichophyton rubrum...
GEOPHILIC Microsporum gypseum...
ZOOPHILIC Microsporum canis: cats and dogs Microsporum nanum: swine Trichophyton
verrucosum: horse and swine…
DERMATOPHYTOSISClinical Classification Infection is named according to the
anatomic location involveda. Tinea barbae e. Tinea pedis
(Athlete’s foot)b. Tinea corporis f. Tinea manuumc. Tinea capitis g. Tinea unguiumd. Tinea cruris
(Jock itch)
Images of dermatophytes infections
T. pedis
Kerion
T. manuumOnychomycosis
Pathogenesis and ImmunityContact and traumaMoistureCrowded living conditionsCellular immunodeficiency
(chronic inf.)Re-infection is possible (but,
larger inoculum is needed, the course is shorter )
Clinical manifestation
Tinea capitis (scalp)Common in childrenTypical lesions," kerion”, scarring,
“alopecia”Favus (Tinea favosa)Debris, yellow cup shaped crustScutulaCicatricial alopeciaT. schoenleinii
Clinical manifestation Cont.
Skin Circular, dry, erythematous, scaly,
itchy lesions Nail Thickened, deformed, friable,
discoloured nails, subungual debris accumulation
DERMATOPHYTOSISTransmissionClose human contactSharing clothes, combs, brushes,
towels, bed sheets. (Indirect)Animal-to-human contact
(Zoophilic)
Human contact Animal contact
Dermatophytes Diagnosis
I. ClinicalAppearanceWood lamp (UV, 365 nm) II. Lab Direct microscopic examination
(10-25% KOH)Ectothrix/endothrix/favus hair
Dermatophytes Diagnosis images
Clinical
KOHEdothrix Ectothrix
Hair invasion by Dermatophytes
Wood lamp
Dermatophytes Diagnosis
CultureMycobiotic agar Sabouraud dextrose agarShould contain antibiotic $
actidione
T. rub rum
M. canis T. vilaceum
Dermatophytes Identification Colony characteristicsMicroscopic morphology genus Macroconidium
Microconidium Microsporum---- fusiform---------------(+) Epidermophyton clavate-----------------(-) Trichophyton-- - (few) cylindrical/ --- --
(+) clavate/fusiform single, in clusters
Microscopic morphology of Microscopic morphology of dermatophytesdermatophytes
Examples
Microsporum canis T rubrum
E. floccosum Chlamydospores
Treatment
Topical Miconazole, clotrimazole econazole, terbinafine...OralGriseofulvinKetaconazole ItraconazoleTerbinafine