Mycosis - fungal diseases are described

1. MYCOSIS

2. ■ MYCOSIS:
A disease caused by infection with a fungus.
■ 3 principal clinical types:
•Superficial mycoses
•Subcutaneous mycoses
•Systemic mycoses

3. ■ SUPERFICIAL MYCOSES:
•These involves the superficial surface of the
body. ie, Dermis
•They are acquired by direct contact, either person to person or
animal to person (dermatophytes).
•These infections rarely disseminate to the deeper structures.
•They produce local inflammatory reactions and spread
contigously.
•They affect the skin, hair shaft and nails.

4. ■ Superficial Mycoses divided into
two:
■ Surface infections:
Eg: Tinea versicolor
Tinea nigra
Piedra
■ Cutaneous infections:
Eg: Dermatophytes

6. ■ TINEA VERSICOLOR
(PITYRIASIS VERSICOLOR):
Fungus: Pityrosponem orbiculare; lipophilic yeast-like fungus.
• It is characterised by mild chronic infection of stratum
corneum.
• there is patchy discoloration of the skin. Commonest sites are
back, abdomen, upper arms..
• Disease is world wide in distribution

9. ■ PIEDRA:
Fungal infection of the hair.
•Two types:
1.Black piedra
2.White piedra
Black piedra:
Fungus: Piedraia hortae
•Characterised by black nodules on hair, shaft of beard and
scalp.

11. ■ White piedra:
Fungus: Trichosporon beigelii
•Characterised by white nodules on hair shaft of
axilla, moustache, beard and sometimes pubic
hair.
•arthrospores can be seen.

13. ■ CUTANEOUS INFECTIONS:
Dermatophytes:
•Are a group of fungi that infect only superficial keratinised
tissue( skin, hair, nails) without involving the living tissue.
•They break down and utilise keratin.
•They are incapable of penetrating subcutaneous tissue.

14. •They cause dermatophytoses, also known tinea/
ringworm.
•Hypersensitivity to fungus antigens is probably
responsible for the sterile vesicular lesions
sometimes seen in sites distant from ringworm.
•These lesions are named dermatophytids.

15. ■ Classification:
Classified into 3 genera:
Genes infection of
1.Trycophyton Hair, skin, nail
2.Microsporum Hair, skin
3.Epidermophyton Skin, nail

16. ■ Classified into 3 based on natural
habitat and host preferences:
1.Anthrapophilic - Man
2.Zoophilic -Animals
3.Geophilic - Soil
•T. rubrum, T. Mentagrophytes, E. Floccosum and M.
Audouinni are examples of anthrapophilic
dermatophytes.
•Eg of zoophilic dermatophytes is M. Canis in dogs
and cats.

17. •Geophilic species are M. Gypsum which occur
naturally in soil.
Important species:
Trichophyton:
•T.rubrum
•T.tonsurans
•T.violaceum
•T.verrocosum

18. ■ Microsporum:
•M.gypsum
•M.canis
•M.audouinii
■ Epidermophyton:
•E.floccosm

19. ■ Clinical aspects of dermatophytosis:
■ Dermatophytosis is twice as common in males as in
females. Clinical classification is according to the
anatomic site involved.
■ Tinea barbae (barber’s itch) involves the bearded
areas of the face and neck.
■ Tinea corporis (Tinea glabrosa) is ringworm of the
smooth or non-hairy skin of the body.
■ Tinea imbricata is a special type of Tinea corporis
found in the tropics, which presents with character-
istic extensive concentric rings of papulosquamous
scaly patches.

20. ■ Tinea capitis is ringworm of the scalp;
favus and kerion are variants.
■ Tinea cruris (jock itch) involves the groin
and perineum.
■ Tinea pedis (athlete’s foot) is ringworm of
the foot.
■ Tinea manuum involves the hand.
■ Tinea unguium involves the nails.

21. TINEA BARBAE
TINEA CORPORIS

22. TINEA IMPRICATA

23. TINEA CAPITIS

24. TINEA CRURIS TINEA PEDIS

25. TINEA MANUUM TINEA UNGUIUM

26. ■ Clinical features:
■ Lesions in the skin tend to be circular, erythematous,
scaly and itchy. Lesions of the hair include kerion,
scarring and alopecia.
■ Favus: A chronic type of ringworm in which dense
crusts (scutula) develop in the hair follicles, leading
to alopecia and scarring
■ Kerion: Severe boggy lesions with marked
inflammatory reaction that sometimes develops in
scalp infection due to dermatophytes. Nails infected
by dermatophytes are deformed, friable and
discoloured, and there is accumulation of debris
under the nails. In lesions, dermatophytes appear as
hyphae and arthrospores.

27. FAVUS KERION

28. ■ Pathogenicity:
■ Mechanisms of pathogenesis are unclear.
Fungal products may be responsible for inciting
local inflammation. Hypersensitivity to fungal
anti- gens result in sterile vesicular lesions
sometimes seen in sites distant from the
ringworm. The reaction may follow oral
antifungal therapy and can be confused with an
allergic drug reaction. These lesions are called
dermatophytids (or the ‘id’ reaction).

29. ■ Laboratory investigations:
1. Specimens: Scrapings of the skin (from the edges of
ringworm lesions) and nail, hair clippings (hair plucked from
the scalp).
2. Microscopic examination: A wet preparation of the specimen
is made by placing the scrapings in a drop of 10-20% potassium
hydroxide (KOH) on a slide, which is then covered by a coverslip
and left for 10-20 minutes to digest the keratin. Additional time
may be required to digest nails. Digestion of keratin (‘clear-
ing’) is helped by gently warming the slide. A positive finding by
direct microscopic examination of the specimen establishes the
diagnosis of ringworm, irrespective of whether culture is
performed.

30. The presence of branching hyaline (non-pigmented)
septate hyphae is considered positive for fungi; spores
may sometimes be seen
■ In suspected Tinea capitis, fungal elements are
looked for in plucked hair. Selection of infected hair
for examination is facilitated by exposure to UV light
(Wood’s lamp). Infected hair will be fluorescent. Two
types of hair infection may be distinguished in wet
mounts : ectothrix, in which arthrospores are seen as
a sheath surround- ing the hair, and endothrix, in
which the spores are inside the hair shaft.

31. 3.Culture:
■ Species identification is possible only by examination of the
culture. The specimen is inoculated onto
■ Sabouraud dextrose neopeptone agar containing
chloramphenicol (the antibiotic suppresses growth of
contaminating bacteria)
■ Sabouraud agar containing chloramphenicol and
cycloheximide (to suppress bacteria and non dermatophytic
filamentous fungi)
■ The plates are incubated aerobically at 25-30°C for up to 21
days, and are checked daily for the appearance of fungal
colonies. Identification of dermatophytes in the laboratory is
by examining the macroscopic characteristics of the fungal
colonies (rate of growth, texture, colour on the observe and
reverse)

32. ■ Trichophyton: Colonies may be powdery, velvety or
waxy,with pigmentation characteristic of different
species.
■ Microsporum: Colonies are cotton-like, velvety or
powdery, with white to brown pigmentation.
■ Epidermophyton: Colonies are powdery and greenish
yellow.

34. ■ Microscopic examination:
• Material teased out from fungal colony(culture
mount) or cellotape mount or slide culture.
•Growth, carefully transferred to a slide as the
structural arrangement is preserved.
•A wet preparation of growth made by staining
with lactophenol cotton blue.
•Hyphae and conidia(asexual spores) observed.
•Conidia 2 types: unicellular microconidia and
septate macroconidia.

35. ■ Trichophyton:
•Microconidia: abundant, arranged in clusters along
the hyphae or borne on conidiophores.
•Macroconidia:Scanty, thin, elongated, with blunt
ends, aids species identification.
•Some species possess special hyphal characters
such as spiral hyphae, racquet mycelium.
•Trichophyton species infect skin, hair and nails.
• T. Rubrum is the common species infecting humans
often causes chronic treatment resistant lesions.

36. ■ Microsporum:
•Microconidia: Relatively scanty, not
distinctive
•Macroconidia:Predominant spore form,
large, multicellular and spindle shaped.
•Microsporum species infect the hair and
skin but usually not the nails.

37. ■ Epidermophyton:
•Colonies are powedery and greenish
yellow.
•Microconidia are absent.
• Macroconidia:multicellular, pear shaped
and typically arranged in clusters.
•Epidermophyton attacks skin and nails but
not hairs.

38. ■ Test for identification of species:
•Based on certain physiological test such as testing
the ability of fungus to,
1.Penetrate the hair under experimental
conditions(in vitro hair perforation test)
2.Hydrolyse urea
3.Grow on polished rice grains and certain special
media.
4.Withstand elevated temperatures ( temperature
tolerance).

39. ■ Hypersensitivity can be demonstrated by skin
testing with fungal antigen, trychophytin.
■ Treatment:
•By tropical agents containing
Azoles(Miconazole, Clotrimazole) and Terbinafine
•Oral preparations of Griseofulvin, Azoles Or
Terbinafine may also be used.

40. ■ Mild infections, treated by tropical imidazole
and severe infection by oral griseofulvin
■ Epidemology and Prevention:
•Dermatophytoses occurs worldwide but
certain species show geographically restricted
distribution.
• Social and cultural patterns as well as age,
hormones and intercurrent diseases affect
susceptibility to dermatophytoses.

41. ■ Habitat:
•Depending on natural habitat dermatophytes are classified as:
1.Anthrapophillic – Humans are the host, cause mild but chronic
lesions.
Eg: T. rubrum, E.floccosum
2.Zoophillic – Natural parasites of animals, in humans cause severe
inflammations that are readily curable.
Eg: T. verrocosum, M. Canis
3.Geophillic – Occur naturally in soil, less pathogenic for humans.
Eg: M. Gypseum, T. ajelloi

42. ■ Control:
•Depends on personal cleanliness, avoiding
contact with infectious materials and effective
treatment.
•Tinea pedis occurs only in people who wear
socks with closed shoes.
•Candida infection of nail, Onychomycosis is
often seen in persons who comes in contact with
water and whose hands are often soggy.