cutaneous mycoses n.
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  1. CUTANEOUS MYCOSES By Dr. Emad AbdElhameed Morad Lecturer of Medical Microbiology and Immunology

  2. Dermatophytes • More than 100 species have been described for dermatophytes, only about 40 are considered and less than half of these are associated with human disease. • Dermatophytes include three genera which are: trichophyton, microsporum and epidermophyton. • According to sporulation: • Asexual (anamorphic state):chains of arthroconidia. • Sexual (teleomorphic state):trichophyton and microsporum are ascomycetes but that of epidermophyton is not observed. Dr. Emad AbdElhameed Morad

  3. Dr. Emad AbdElhameed Morad

  4. Trichophyton Affect • Skin • Hair • Nails Dr. Emad AbdElhameed Morad

  5. Microsporum Affect • Skin • Hair Dr. Emad AbdElhameed Morad

  6. Epidermophyton Affect • Skin • Nails Dr. Emad AbdElhameed Morad

  7. Pathogenesis • Dermatophytes affect keratinized tissues (skin, hair and nails) as they produce keratinase enzyme which digests the keratin. • The intact skin is an important barrier against infection. • Heat and humidity enhance the infection. • Infection may be: • Anthropophilic: from man to man by direct contact. • Zoophilic: from the animals. • Geophilic: from the soil. Dr. Emad AbdElhameed Morad

  8. Anthropophilic group tends to cause chronic infections which are difficult to cure. • Zoophilic and geophilic groups tend to cause acute inflammatory lesions that respond well to therapy. Dr. Emad AbdElhameed Morad

  9. Dr. Emad AbdElhameed Morad

  10. Clinical picture • The lesion is called ring worm or tinea. • Tinea comes from the latin word moth. • The lesion is called ring worm because it is ring shaped with red raised border of active inflammation and a healing center. • The clinical forms of the disease are: • Tinea capitis (head) & tinea cruris (groin area) & tinea corporis (body) & tinea unguium (nails) & tinea pedis (feet) & tinea barbae (beard) & tinea manus (hands). Dr. Emad AbdElhameed Morad

  11. Tinea capitis(scalp) Dr. Emad AbdElhameed Morad

  12. Tinea cruris(jock itch) Dr. Emad AbdElhameed Morad

  13. Tinea corporis(the body) Dr. Emad AbdElhameed Morad

  14. Tinea unguium (onychomycosis)Nails are thickened, discolored and brittle Dr. Emad AbdElhameed Morad

  15. Tinea pedis The lesion is called athlete’s foot that occurs in those wearing shoes Dr. Emad AbdElhameed Morad

  16. Tinea barbae(bearded area) Dr. Emad AbdElhameed Morad

  17. Favusis a form of tinea capitis which is caused by Trichophyton schoenleinii. Favus comes from the latin word honey comb. In favus waxy crusts called scutula surround the hair follicles. • Kerionis a severe lesion in the scalp which is caused by inflammation and hypersensitivity to zoophilic fungi. Dr. Emad AbdElhameed Morad

  18. Dermatophytid reaction:in the course of dermatophytosis, the individual may become hypersensitive to fungal elements and develop allergic manifestations called dermatophytids usually vesicles elsewhere in the body most often on the hand. Trichophytin skin test is markedly positive. Dr. Emad AbdElhameed Morad

  19. Laboratory diagnosis • Wood’s light (UV light at wave length 365 nm): • Microsporum lesions will fluoresce brilliant green. • Specimen: • Skin scales, nails, hair. • Microscopic examination of these specimens using KOH 10%: • KOH dissolves keratin but does not affect fungi. Branching septate hyphae are detected among epithelial cells. • Spores (arthroconidia) may be detected outside the hair shaft (ectothrix) or inside the hair shaft (endothrix). An exception is favus in which hyphal elements are seen in the hair shafts. Dr. Emad AbdElhameed Morad

  20. Specimen collection Dr. Emad AbdElhameed Morad

  21. Dermatophytes in KOH mount of skin scraping(Branching hyphae + arthroconidia) Dr. Emad AbdElhameed Morad

  22. Ectothrix and endothrix infection Endothrix spores (T. tonsurans) Ectothrix spores (Microsporum) Dr. Emad AbdElhameed Morad

  23. (Favic hair)In favic hair, hyphae do not form spores but can be found within the hair shaft Dr. Emad AbdElhameed Morad

  24. Culture: • Medium: Sabouraud’s dextrose agar to which we add chloramphenicol and cycloheximide. • Incubation: at the room temperature. • Duration: Up to 4 weeks. • Identification is done by: • Morphology and color on the observe and reverse surfaces. • Slide culture to study the morphology and color of conidia using lactophenol cotton blue. Dr. Emad AbdElhameed Morad

  25. Trichophyton mentagrophytes Conidia:are macroconidia which are smooth, thin walled and cylindrical and microconidia which are grape like clusters on terminal branches. Colonies may be cottony to granular. Dr. Emad AbdElhameed Morad

  26. Spiral hyphae Dr. Emad AbdElhameed Morad

  27. Trichophyton rubrum Conidia:are microconidia which are small and piriformin shape. The fungus has white cottony observe surface + deep red non diffusible pigment on the reverse surface Dr. Emad AbdElhameed Morad

  28. Dr. Emad AbdElhameed Morad

  29. Microsporum canis Conidia:are macroconidia which are thick echinulate walled, 8-15 cells + curved tip The fungus has white cottony observe surface + deep yellow on the reverse surface Dr. Emad AbdElhameed Morad

  30. Dr. Emad AbdElhameed Morad

  31. Microsporum gypseum Conidia:are macroconidia which are thin echinulate walled, 4 – 6 cells Colonies of the fungus are tan powdery. Dr. Emad AbdElhameed Morad

  32. Epidermophyton floccosum Conidia: are macroconidia which are smooth walled, clavate, 2 – 4 cells, groups of two or three Colonies of the fungus are flat, velvety with olive green tinge. Dr. Emad AbdElhameed Morad

  33. Treatment • For skin infections: topical azoles (miconazole, clotrimazole). They act by inhibiting ergosterol synthesis. • For hair infections: griseofulvin. It acts by inhibiting the microtubule function in the fungus. Dr. Emad AbdElhameed Morad