Superficial Mycoses Mycology

By,
MANEESHA M JOSEPH
Assistant Professor
Baby Memorial College
MANEESHA M JOSEPH 1
Video Class of this Topic is uploaded in YouTube Channel MALLU MEDICOS LOUNGE

SUPERFICIAL MYCOSES
v These are superficial cosmetic fungal infections of the skin or hair
shaft.
v No living tissue is invaded and there is no cellular response from the
host. Essentially no pathological changes are elicited.
v These infections are often so innocuous that patients are often
unaware of their condition.
MANEESHA M JOSEPH 2

MALASSEZIA
v Malassezia species may cause various skin manifestations including
pityriasis versicolor, seborrhoeic dermatitis, dandruff, atopic eczema and
folliculitis.
v Initially called as tinea versicolor under the misconception that disease is
caused by one of the dermatophyte
v M.furfur is a part of normal skin flora of man and most of the infections are
endogenous
v It is found in areas of body rich in sebaceous glands.
v Fungaemia due to lipid-dependent Malassezia species usually occurs in
patients with central line catheters receiving lipid replacement therapy,
especially in infants
MANEESHA M JOSEPH 4

Clinical Manifestations
A) PITYRIASIS VERSICOLOR:
This is a chronic, superficial fungal disease of the skin characterised by well-demarcated
white, pink, fawn, or brownish lesions, often coalescing, and covered with thin furfuraceous
scales
v Causative agent is Malassezia furfur which is a lipophilic yeast like fungus
v The colour varies according to the normal pigmentation of the patient, exposure of the
area to sunlight, and the severity of the disease.
v Lesions are asymptomatic and only cosmetic importance to patient 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.
v Young adults are affected most often, but the disease may occur in childhood and old
age.
MANEESHA M JOSEPH 5

Rapid and easy way to confirm the diagnosis of tinea versicolor is by using a
Wood's lamp. Yellow to yellow- green fluorescence is characteristic of fine
scales taken from active lesions. Although the sensitivity of this procedure is
reduced when patients have taken a recent shower
Wood’s lamp: longwave UV light used in dark room will cause Tinea
microbes to fluoresce. This image is of an affected scalp.
MANEESHA M JOSEPH 8

B) PITYRIASIS FOLLICULITIS:
This is characterised by follicular papules and pustules localised to
the back, chest and upper arms, sometimes the neck, and more
seldom the face.
v These are itchy and often appear after sun exposure.
v Scrapings or biopsy specimens show numerous yeasts occluding
the mouths of the infected follicules.
v Most cases respond well to topical imidazole treatment, however
patients with extensive lesions often require oral treatment with
ketoconazole or itraconazole.
v Once again, prophylactic treatment once or twice a week is
mandatory to prevent relapse.
MANEESHA M JOSEPH 9

C) 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.
v 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 ( blockage)
v Patients with neurological diseases such as Parkinson's disease and those with AIDS are
commonly affected.
v Clinical manifestations are characterised by erythema and scaling in areas with a rich supply of
sebaceous glands ie the scalp, face, eyebrows, ears and upper trunk.
v Lesions are red and covered with greasy scales and itching is common in the scalp.
v The clinical features are typical and skin scrapings for a laboratory diagnosis are unnecessary.
v the use of a topical imidazole is recommended, especially ketoconazole which has proved to be
the most effective agent.
v Relapse is common and retreatment when necessary is the simplest approach for long term
management.
MANEESHA M JOSEPH 10

D)FUNGAEMIA:
Malassezia has also been reported as causing catheter acquired
fungaemia in neonate and adult patients undergoing lipid replacement
therapy.
v Such patients may also develop small embolic lesions in the lungs or
other organs.
v Diagnosis requires special culture media and blood drawn back
through the catheter is the preferred specimen.
v Culture of the catheter tip is also recommended.

Laboratory Diagnosis:
1. Clinical Material:
Skin scrapings from patients with superficial lesions, blood and indwelling
catheter tips from patients with suspected fungaemia.
v 2. 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 :-
v thick-walled round, budding yeast-like cells with occasional budding and
short angular hyphal forms that may be curved and inadequately branched
up to 8um in diameter characteristic
” banana and grapes” / "spaghetti and meatballs

GMS stained skin biopsy showing characteristic spherical yeast
cells and short pseudohyphal elements typical of M. furfur.

10% KOH with Parker ink mount showing characteristic spherical yeast cells and
short pseudohyphal elements typical of the fungus

3. 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 . Small
creamy yellow colonies appear within 5-7 days.
or
use a more specialized media like Dixon's agar which contains glycerol
mono-oleate (a suitable substrate for growth).
.

Culture of M. furfur on Dixon's agar.

Colony appearance of Malassezia furfur (right)
and Malassezia sympodialis (left) on modified Dixon agar containing L-tryptophan
as a single source of nitrogen. Specific brownish pigment diffusion into the medium is
observed only in M.furfur

v Management:
The most appropriate antifungal treatment for pityriasis versicolor is to use a topical imidazole
in a solution or lathering preparation.
v Ketoconazole shampoo has proven to be very effective.
v 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.
v 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.
v 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.
v Relapse is a regular occurrence and prophylactic treatment with a topical agent once or twice
a week is often necessary to avoid recurrence.

TINEA NIGRA
v A superficial fungal infection of skin characterised by
brown to black macules which usually occur on the
palmar aspects of hands and occasionally the plantar
and other surfaces of the skin.
v World-wide distribution, but more common in tropical
regions of Central and South America, Africa, South-
East Asia and Australia.
v The aetiological 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.

Clinical Manifestations:
v Skin lesions are characterised by brown to black macules which usually occur on
the palmar aspects of hands and occasionally the plantar and other surfaces of the
skin.
v Rarely occur on neck,chest
v Patient may initialy notice a dark macule that slowly enlarges over a period of
week .
v Lesion vary in size from few mm to several cm in diameter.
v Lesions are non-inflammatory and non-scaling. Familial spread of infection has
also been reported.
Note:
There is no inflammatory reaction.

Skin scrapings.
2. Direct Microscopy:
Skin scrapings should be examined using 10% KOH
and Parker ink or calcofluor white mounts
Brown,septate branching hyphae or budding yeast
cells in KOH wet mount
Laboratory Diagnosis
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

Microscopic morphology of Exophiala werneckii showing the typical
2-celled, pale brown yeast cells, with prominent darkly-pigmented
septa, which act as annellides. Annellides may also arise from the
hyphae. Annelloconidia are 1 to 2-celled, cylindrical to spindle- shaped,
hyaline to pale brown and usually occur in aggregated mass3e5s.MANEESHA M JOSEPH 22

Ø 3. Culture:
Clinical specimens should be inoculated onto primary isolation
media, like Sabouraud's dextrose agar.
Ø Organism grows slowly as shiny,moist,adherent ,yeast like
colony
Ø Initially colony is brown ,but rapidly becomes olive to shiny
,greenish black with black pigmentation in reverse.
Ø Growth on microscopic examination shows budding yest like
cells with occasional septa

Exophiala werneckii on Sabouraud's dextrose agar. Initially colonies are
mucoid, yeast-like and shiny black. However with age they develop
abundant aerial mycelia and become dark olivaceousin colour. 34MANEESHA M JOSEPH 24

Management:
Usually, topical treatment with Whitfield's ointment
(benzoic acid compound) or an imidazole agent twice a
day for 3-4 weeks is effective.

WHITE PIEDRA
v White piedra is a superficial cosmetic fungal infection of the hair shaft caused
by Trichosporon beigelii.
v Infected hairs develop soft greyish-white nodules along the shaft.
v Essentially no pathological changes are elicited.
v White piedra is found worldwide, but is most common in tropical or subtropical regions.
v Trichosporon species are a minor component of normal skin flora, and are widely
distributed in nature.
v 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.
v Disseminated infections are most frequently (75%) caused by T. asahii and have been
associated with leukaemia,

vInfections are usually localised to the axilla or scalp but may also be
seen on facial hairs and sometimes pubic hair. White piedra is
common in young adults.
vThe presence of irregular, soft, white or light brown nodules, 1.0-1.5
mm in length, firmly adhering to the hairs is characteristic of white
piedra.

White Piedra: soft spongy
nodes all along hair shaft
45
These nodules are a loose
aggregate of hyphae and
arthroconidia

Laboratory Diagnosis:
Epilated hairs with white soft nodules present on the shaft.
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.

KOH and Parker ink mount of a hair nodules of
white piedra showing yeast-like cells
of Trichosporon spp.
KOH and Parker ink mount of a hair nodules of white
piedra showing yeast-like cells of Trichosporon spp.

Direct mycological exam exhibiting a
yellowish nodule around a hair shaft,
formed by hyphae andarthrospores
Culture in Sabouraud's agar - yeast-like
colony, cream colored, wrinkled and with a
wax-like appearance
KOH mount of affected hair showing a
cluster of blastoconidia around thehair
Sabouraud’s agar showing growth of
soft cream coloured wrinkled colonies of
T. beigelii 46MANEESHA M JOSEPH 31

Culture:
Hair fragments should be implanted onto primary isolation media, like Sabouraud's
dextrose agar. Colonies of Trichosporon spp. are white or yellowish to deep cream
colored, smooth, wrinkled, velvety, dull colonies with a mycelial fringe.
4. Serology:
Not required for diagnosis.
5. Identification:
Characteristic clinical, microscopic and culture features.
Causative agents:
Trichosporon spp. Six species are of clinical significance: T. asahii, T. asteroides, T.
cutaneum, T. inkin, T. mucoides and T. ovoides. Other species reported from human
and animal infections include T. dermatis, T. domesticum, T. faecale, T. jirovecii, T.
loubieri and T. mycotoxinovorans (

Culture of hairs showing growth of Trichosporon spp. typical of white piedra
Management:
Shaving the hairs is the
simplest method of
treatment. Topical
application of an imidazole
agent may be used to
prevent reinfection.

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.
v Infections are usually localised to the scalp but may also be seen on hairs of the beard, moustache
and pubic hair.
v Black piedra mostly affects young adults and epidemics in families have been reported following
the sharing of combs and hairbrushes.
v Infected hairs generally have a number of hard black nodules on the shaft.
v Black piedra may be confused with trichorrhexis nodosa and trichonodosis but mycological
examination will always confirm the diagnosis.

Epilated hairs with hard black nodules present on the shaft.
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.

3. 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.
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.

hard, difficult toBlack Piedra:
remove, black.The nodule is the
ascomycete fruiting
body of the fungus, know
as an ascostroma
39MANEESHA M JOSEPH 37

(a) 10% potassium hydroxide (KOH) examination of black colored nodule
shows a concretion forming a collar around hair shaft. Concretion was
made up of filamentous hyphae, held together in a mass by cement like
substance. Spores are seen at the edges of the nodule (←),
(b) KOH mount of crushed nodule shows brown dematiaceous closely
septate hyphae (H) with few chlamydospores(Ch).
(c) Culture on Sabouraud's dextrose agar shows small, compact, blackish
colonies with velvetysurface.
(d) (d) Microscopic examination of the colonies showed round, dark bro4w0n,
globus ascus (→) withascospores
Piedraia hortae

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