dermatomycosis

1. Department of Microbiology
Submitted to : Miss Poornima Chhaya
By:
Reg. no : 16VQSM6001
M.Sc. Microbiology(3rd sem)

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. 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.  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. Dermatophytes and their Hosts

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. 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. 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).

11. 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.

12. 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.

13.  Epidermophyton:
 Colony of Epidermophyton flocosum is white yellow or
olive in color.
 These are identified by multiple smooth walled , club
shaped macro conidia.

14. Culturing: a) T.rubrum; b)
E.floccosum; c) T.mentagrophytes; d)
M.canis

15. 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.

16. 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.

17. 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.