ppt

1. Superficial Mycoses
By Habtamu Biazin (Asst. prof )
Dept of MIP
4/1/2023 1

2. Superficial Mycoses
• These are superficial cosmetic fungal infections of the skin or hair shaft.
• No living tissue is invaded
• There is no cellular response from the host.
• Essentially no pathological changes are elicited.
• These infections are often so innocuous that patients are often unaware of their
condition.
4/1/2023 2

3. Superficial Mycoses…
Disease Causative organisms Incidence
Pityriasis versicolor
Seborrhoeic dermatitis
including Dandruff and
Follicular pityriasis
Malassezia spp.
(a lipophilic yeast)
Common
Tinea nigra Hortaea werneckii Rare
White piedra Trichosporon spp. Common
Black piedra Piedraia hortae Rare
4/1/2023 3

4. 1. Malassezia infection
• Malassezia species are basidiomycetous yeasts
• Part of the normal skin flora of humans and animals
• The genus now includes 14 species of which 13 are lipid dependent.
• These include:
4/1/2023 4

5. Malassezia infection …
Malassezia species Host
M. caprae Goat, horse
M. dermatis Human
M. equina horse, cow
M. furfur Human , cow, elephant, pig, monkey, ostrich, pelican
M. globosa Human , cheetah, cow
M. japonica Human
M. nana cat, cow, dog
M. obtusa Human
M. pachydermatis dog, cat, carnivores, birds
M. restricta Human
M. slooffiae Human , pig, goat, sheep
M. sympodialis Human, horse, pig sheep
M. yamatoensis Human
(Cabanes et al. 2011)
4/1/2023 5

6. Malassezia infection…
• M. sympodialis, M. globosa, M. slooffiae and M. restricta are the most frequently
found species responsible for colonization of humans (Arendrup et al. 2014).
• Malassezia species may cause various skin manifestations including pityriasis
versicolor, seborrhoeic dermatitis, dandruff, atopic eczema and folliculitis.
• M. pachydermatis is known to cause external otitis in dogs.
• Fungaemia due to lipid-dependent Malassezia species usually occurs in patients
with central line catheters receiving lipid replacement therapy, especially in infants
4/1/2023 6

7. Clinical manifestations
• Pityriasis versicolor:
• This is a chronic, superficial fungal disease of the skin characterized by well-demarcated
white, pink, fawn, or brownish lesions, often coalescing, and covered with thin furfuraceous
scales.
• The colour varies according to the normal pigmentation of the patient, exposure of the area to
sunlight, and the severity of the disease.
• Lesions occur on the trunk, shoulders and arms, rarely on the neck and face, and fluoresce a
pale greenish colour under Wood's ultra-violet light.
• Young adults are affected most often, but the disease may occur in childhood and old age.
4/1/2023 7

8. Clinical manifestations
Pityriasis versicolor showing hyperpigmented lesions.
4/1/2023 8

9. Clinical manifestations…
• Pityriasis folliculitis:
• This is characterized by follicular papules and pustules localized to the back, chest and upper
arms, sometimes the neck, and more seldom the face.
• These are itchy and often appear after sun exposure.
• Scrapings or biopsy specimens show numerous yeasts occluding the mouths of the infected
follicules.
• Most cases respond well to topical imidazole treatment, however patients with extensive
lesions often require oral treatment with ketoconazole or itraconazole.
• Once again, prophylactic treatment once or twice a week is mandatory to prevent relapse.
4/1/2023 9

10. Clinical manifestations…
Pityriasis folliculitis
4/1/2023 10

11. Clinical manifestations…
• Seborrhoeic dermatitis and dandruff:
• Current evidence suggests Malassezia, combined with multifactorial host factors is also the
direct cause of seborrhoeic dermatitis, with dandruff being the mildest manifestation.
• Host factors include genetic predisposition, an emotional component (possible endocrine or
neurologically mediated factors), changes in quantity and composition of sebum (increase in
wax esters and a shift from triglycerides to shorter fatty acid chains), increase in alkalinity of
skin (due to eccrine sweating) and external local factors such as occlusion.
• Patients with neurological diseases such as Parkinson's disease and those with AIDS are
commonly affected.
4/1/2023 11

12. Clinical manifestations…
• Seborrhoeic dermatitis and dandruff:
• Clinical manifestations are characterized by erythema and scaling in areas with a rich supply
of sebaceous glands i.e. the scalp, face, eyebrows, ears and upper trunk.
• Lesions are red and covered with greasy scales and itching is common in the scalp.
• The clinical features are typical and skin scrapings for a laboratory diagnosis are unnecessary.
• Once again, the use of a topical imidazole is recommended, especially ketoconazole which has
proved to be the most effective agent.
• Relapse is common and retreatment when necessary is the simplest approach for long term
management.
4/1/2023 12

13. Clinical manifestations…
• Fungaemia:
• Malassezia has also been reported as causing catheter acquired fungaemia in
neonate and adult patients undergoing lipid replacement therapy.
• Such patients may also develop small embolic lesions in the lungs or other
organs.
• Diagnosis requires special culture media and blood drawn back through the
catheter is the preferred specimen.
• Culture of the catheter tip is also recommended.
4/1/2023 13

14. Laboratory diagnosis:
• Clinical material:
• Skin scrapings from patients with superficial lesions, blood and indwelling catheter tips from
patients with suspected fungaemia.
• Direct microscopy:
• Skin scrapings taken from patients with Pityriasis versicolor stain rapidly when mounted in
10% KOH, glycerol and Parker ink solution and
• show characteristic clusters of thick-walled round, budding yeast-like cells and short angular
hyphal forms up to 8um in diameter (ave. 4um diam.).
• These microscopic features are diagnostic for Malassezia furfur and culture preparations are
usually not necessary.
4/1/2023 14

15. Laboratory diagnosis:
GMS stained skin biopsy showing characteristic spherical yeast
cells and short pseudohyphal elements typical of M. furfur; and
4/1/2023 15
10% KOH with Parker ink mount showing characteristic
spherical yeast cells and short pseudohyphal elements typical
of the fungus.

16. Laboratory diagnosis…
• Culture:
• Culture is only necessary in cases of suspected fungaemia.
• M. furfur is a lipophilic yeast, therefore in vitro growth must be stimulated by
natural oils or other fatty substances.
• The most common method used is to overlay Sabouraud's dextrose agar
containing cycloheximide (actidione) with olive oil or
• alternatively to use a more specialized media like Dixon's agar which contains
glycerol mono-oleate (a suitable substrate for growth).
4/1/2023 16

17. Laboratory diagnosis:
Culture of M. furfur on Dixon's agar.
Identification:
• Microscopic evidence of unipolar,
broad base budding yeast cells and
special lipid requirements for growth
in culture are usually diagnostic.
4/1/2023 17

18. Laboratory diagnosis…
• Serology:
• There are currently no commercially available serological procedures for the
diagnosis of Malassezia infections.
4/1/2023 18

19. Management:
• The most appropriate antifungal treatment for pityriasis versicolor is to use a topical imidazole in a
solution or lathering preparation.
• Ketoconazole shampoo has proven to be very effective.
• Alternative treatments include zinc pyrithione shampoo or selenium sulfide lotion applied daily for
10-14 days or the use of propylene glycol 50% in water twice daily for 14 days.
• In severe cases with extensive lesions, or in cases with lesions resistant to topical treatment or in
cases of frequent relapse oral therapy with itraconazole [200 mg/day for 5-7 days] is usually
effective.
4/1/2023 19

20. Management…
• Mycologically, yeast cells may still be seen in skin scrapings for up to 30 days following treatment,
thus patients should be monitored on clinical grounds.
• Patients also need to be warned that it may take many months for their skin pigmentation to return
to normal, even after the infection has been successfully treated.
• Relapse is a regular occurrence and prophylactic treatment with a topical agent once or twice a
week is often necessary to avoid recurrence
4/1/2023 20

21. 2. Tinea nigra
• A superficial fungal infection of skin
• Characterized by brown to black macules which usually occur on the palmar aspects of
hands and occasionally the plantar and other surfaces of the skin.
• World-wide distribution
• More common in tropical regions of Central and South America, Africa, South-East Asia
and Australia.
• The etiological agent is Hortaea werneckii a common saprophytic fungus believed to
occur in soil, compost, humus and on wood in humid tropical and sub-tropical regions.
4/1/2023 21

22. Tinea nigra…
• Clinical manifestations:
• Skin lesions are characterized by brown to black macules which usually occur on the
palmar aspects of hands and occasionally the plantar and other surfaces of the skin.
• Lesions are non-inflammatory and non-scaling.
• Familial spread of infection has also been reported
• There is no inflammatory reaction
4/1/2023 22

23. Tinea nigra
Typical brown to black, non-scaling macules on the palmar aspect of the
hands. Note: there is no inflammatory reaction.
4/1/2023 23

24. Laboratory diagnosis
Clinical material: Skin scrapings
• Direct microscopy: Skin scrapings should be examined using 10% KOH and
Parker ink or calcofluor white mounts.
Skin scrapings mounted in 10% KOH showing pigmented brown to dark olivaceous (dematiaceous) septate hyphal
elements and 2-celled yeast cells producing annelloconidia typical of Hortaea werneckii.
4/1/2023 24

25. Laboratory diagnosis…
• Culture:
• Clinical specimens should be inoculated onto primary isolation media, like SDA.
• Identification: Characteristic clinical, microscopic and culture features.
• Causative agents: Hortaea werneckii
Colony and conidia of Hortaea werneckii
4/1/2023 25

26. Laboratory diagnosis:
• Serology: Not required for diagnosis
• Management:
• Usually, topical treatment with Whitfield's ointment (benzoic acid compound) or
• an imidazole agent twice a day for 3-4 weeks is effective
4/1/2023 26

27. 3. White piedra
• White piedra is a superficial cosmetic fungal infection of the hair shaft caused by Trichosporon spp.
• Infected hairs develop soft greyish-white nodules along the shaft.
• Essentially no pathological changes are elicited.
• White piedra is found worldwide, but is most common in tropical or subtropical regions.
• Trichosporon species are a minor component of normal skin flora, and are widely distributed in
nature.
• They are regularly associated with the soft nodules of white piedra, and
• Have been involved in a variety of opportunistic infections in the immunosuppressed patient
4/1/2023 27

28. White piedra …
• Disseminated infections are
• most frequently (75%) caused by T. asahii
• have been associated with leukaemia, organ transplantation, multiple myeloma, aplastic
anaemia, lymphoma, solid tumours and AIDS
• are often fulminate and widespread
• lesions occurring in the liver, spleen, lungs and gastrointestinal tract
• Infections in non-immunosuppressed patients include
Endophthalmitis after surgical extraction of cataracts,
Endocarditis usually following insertion of prosthetic cardiac valves,
Peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD), and
Intravenous drug abuse
4/1/2023 28

29. White piedra …
• Clinical manifestations:
• Infections are usually localized to the axilla or scalp
• May also be seen on facial hairs and sometimes pubic hair.
• White piedra is common in young adults.
• White Piedra is characterized by
• The presence of irregular, soft, white or light brown nodules, 1.0-1.5 mm
in length, firmly adhering to the hairs.
4/1/2023 29

30. White piedra …
White piedra showing soft, light brown nodules, adhering to the hairs.
4/1/2023 30

31. Laboratory diagnosis:
Clinical material:
• Epilated hairs with white soft nodules present on the shaft.
• Direct microscopy:
• Hairs should be examined using 10% KOH and Parker ink or calcofluor white
mounts.
• Look for irregular, soft, white or light brown nodules, 1.0-1.5 mm in length,
firmly adhering to the hairs.
4/1/2023 31

32. Laboratory diagnosis…
KOH and Parker ink mount of a hair nodules of white piedra showing yeast-like cells of Trichosporon spp.
4/1/2023 32

33. Laboratory diagnosis…
• Culture:
• Hair fragments should be implanted onto primary isolation media, like SDA.
• Colonies of Trichosporon spp. are white or yellowish to deep cream colored, smooth,
wrinkled, velvety, dull colonies with a mycelial fringe.
• Serology: Not required for diagnosis
• Identification:
• Characteristic clinical, microscopic and culture features.
4/1/2023 33

34. Laboratory diagnosis…
Culture of hairs showing growth of Trichosporon app. typical of white piedra
4/1/2023 34

35. Causative agents:
• The taxonomy of Trichosporon has been redefined:
• Trichosporon cutaneum, T. dermatis, T. jirovecii and T. mucoides have now been
transferred to the new genus Cutaneotrichosporon, while Trichosporon domesticum,
T. loubieri and T. mycotoxinovorans have now been included into the re-defined
genus Apiotrichum.
• Four species Trichosporon asahii, T. asteroides, T. inkin, and T. ovoides are the most
common clinical isolates, however, T. cormiiforme, T. dohaense ,T. faecale, T.
japonicum and T. lactis have also been reported from human and animal infections
• Importantly, all species are resistant to echinocandins
4/1/2023 35

36. Management:
• Shaving the hairs is the simplest method of treatment.
• Topical application of an imidazole agent may be used to prevent reinfection.
4/1/2023 36

37. 4. Black piedra
• Black piedra is a superficial fungal infection of the hair shaft caused by Piedra
hortae.
• An ascomycetous fungus forming hard black nodules on the shafts of the scalp,
beard, moustache and pubic hair.
• It is common in Central and South America and South-East Asia.
4/1/2023 37

38. Clinical manifestations:
• Infections are usually localized to the scalp
• may also be seen on hairs of the beard, moustache and pubic hair.
• Mostly affects young adults and
• Epidemics in families have been reported following the sharing of combs and
hairbrushes.
• Infected hairs generally have a number of hard black nodules on the shaft.
• Black piedra may be confused with trichorrhexis nodosa and trichonodosis but
mycological examination will always confirm the diagnosis.
4/1/2023 38

39. Laboratory diagnosis
• Clinical material: Epilated hairs with hard black nodules present on the shaft.
• Direct microscopy:
• Hairs should be examined using 10% KOH and Parker ink or calcofluor white. Look for darkly pigmented nodules that may
partially or completely surround the hair shaft.
• Nodules are made up of a mass of pigmented with a stroma-like centre containing asci.
• Culture: Hair fragments should be implanted onto primary isolation media, like Sabouraud's dextrose agar.
Colonies of Piedra hortae are dark, brown-black and take about 2-3 weeks to appear.
• Serology: Not required for diagnosis.
• Identification: Characteristic clinical, microscopic and culture features.
• Causative agents: Piedra hortae
4/1/2023 39

40. Management:
• The usual treatment is to shave or cut the hairs short, but this is often not
considered acceptable, particularly by women.
• In-vitro susceptibility tests have shown that Piedra hortae is sensitive to
terbinafine
• it has been successfully used, at a dose of 250 mg a day for 6 weeks
4/1/2023 40

41. 4/1/2023 41