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  1. 1. Department of Microbiology Submitted to : Miss Poornima Chhaya By: Reg. no : 16VQSM6001 M.Sc. Microbiology(3rd sem)
  2. 2. Introduction  For a long time fungi were regarded as a primitive branch of the vegetable kingdom. Nowadays they are viewed as a separate group, alongside plants, animals, protists and prokaryote organisms.  Fungi are everywhere, occurring both in the sea, in fresh water and on land. There are some 100,000 known species. They constitute an important link in the organic chains of nature by converting dead and decaying matter into new raw materials for plants.
  3. 3. Etiology of Dermatomycosis  Dermatophytons of 3 genera: Trichophyton, Microsporum and Epidermophyton  Keratophytons of some yeast species: Pityrosporum ovale, Pityrosporum orbiculare, Malassezia furfur.  Candida genus (Candida albicans).  Pseudofungi (Corynebacterium minutissimum and Actinomyces israelii.  Moulds (Scopulariopsis, Aspergillus, Penicillium, etc.)
  4. 4.  Dermatomycoses are infections of the skin, hair or nails by fungi. The principal causative agents are dermatophytes, which are subdivided into three groups (genera): Microsporum spp., Trichophyton spp. and Epidermophyton floccosum. The three genera are distinguished by the form of the spores, or macroconidia.  Trichophyton: thin-walled, smooth, four to six septa  Microsporum: thick-walled, with projections five to more septa  Epidermophyton: thick-walled, pear to oval shaped four or fewer septa.
  5. 5. Dermatophytes and their Hosts
  6. 6. Modes of transmission: Dermatophytes are transmitted by direct contact with infected host (human or animal).  By direct or indirect contact with infected exfoliated skin or hair in clothing, combs, hair brushes, theatre seats, caps, furniture, bed linens, shoes, socks, towels, hotel rugs, bathhouse, and locker room floors.
  7. 7. Pathogenesis 1. TRICHOPHYTON: 21 different spp. Are identified which causes infection of hair , skin and nails. -Trichophyton rubrum is the most common offender. -Endothrix: grow entirely within the hair shaft and break of hair, eg. Trichophyton violaceum . -Ectothrix: grow around but outside of hair . - Ecto and Endothrix fungi destroy keratin of hair giving raise to broken hair. 2. MICROSPORUM: 17 spp. Are identified which cause infection of hair and skin -nails are not usually affected. -penetrate the hair and extend down shaft as fine filament.
  8. 8. 3. EPIDERMOPHYTON: superficial and cutaneous mycoses, including E. floccosum, and causes:  Tinea corporis (ringworm),  Tinea cruris (jock itch),  Tinea pedis(athlete’s foot), and  Tinea unguium(fungal infection of the nail bed).
  9. 9. LAB DIAGNOSIS  Specimen -scrapings of skin or nail and short lengths of plucked hair from suspected area.  Processing of specimen : -KOH (10 to 20%) mount of keratinised specimen shows filamentous branching hyphae.  Culture : -specimen is inoculated on plate of SDA containing chloramphenicol and cyclohexamine. -incubation is carried out aerobically at 25 to 30 degree Celsius upto 3 weeks.
  10. 10. 1. Trychophyton 2. Microsporum Trychophyton:  colonies of trichophyon show colors. Conidia are sparse , thin walled , smooth and septate and pencil shaped. Microsporum:  can be identified on scalp because of bright green appearance of infected hair with UV. -microconidia which are numerous thick walled and rough and spindle shaped.
  11. 11.  Epidermophyton:  Colony of Epidermophyton flocosum is white yellow or olive in color.  These are identified by multiple smooth walled , club shaped macro conidia.
  12. 12. Culturing: a) T.rubrum; b) E.floccosum; c) T.mentagrophytes; d) M.canis
  13. 13. TREATMENT Mild infection: Severe infection:  Imidazole (Clotrimazole and Miconazole) cures the infection.  Trychophyton rubrum is often resristant to therapy.  Griseofulvin tablets to be taken for 4 to 6 weeks for skin infection.  One year for nail infection.
  14. 14. Prevention  Avoid sharing clothing, sports equipment, towels, or sheets.  Wash clothes in hot water with fungicidal soap after suspected exposure to ringworm.  Avoid walking barefoot; instead wear appropriate protective shoes in locker rooms and sandals at the beach.  Avoid touching pets with bald spots, as they are often carriers of the fungus.
  15. 15. References  Geo. F. Brooks , Janet S. Butel , Stephen A. Morse(2001) Medical microbiology(22nd ed.) McGraw-hill.  Ananthanarayan & Paniker(2013)Textbook of microbiology(9th ed.) universities press , Hyderabad , India.