SUPERFICIAL & CUTANEOUS

MYCOSES

MYCOSES→ fungal infections acquired by man through inhalation

or inoculation by trauma into the skin

MYCOSES AND MYCOTIC INFECTIONS

→ only about 100 species of yeasts and molds cause disease in humans and animals

→ Dermatophytes and Candida species are commonly transmitted between humans

RISK FACTORS

→ Immunocompromised due to long-term antibiotic treatment

Use of immunosuppressive drugs: Cancer chemotherapy drugs, Corticosteroids

Drugs that prevent organ rejection

Disorders: AIDS, Burns, if extensive ; Diabetes ; Hodgkin lymphoma or other lymphomas; Kidney failure ; Lung

disorders, such as emphysema ; Leukemia

CLASSIFICATION OF MYCOSES

Superficial Mycoses Cutaneous MycosesSubcutaneous MycosesSystemic MycosesOpportunistic Mycoses

SUPERFICIAL MYCOSES

Noninvasive skin, hair, or nails

No cellular response from host

No pathological changes

Host unaware

Disease Causative Organisms

Incidence

Pityriasis versicolor

Seborrhoeic dermatitis including Dandruff

Follicular pityriasis

Malassezia furfur

(a lipophilic yeast)

Common

Tinea nigra Exophiala werneckii

Rare

White Piedra Trichosporon beigelii

Common

Black Piedra Piedraia hortae

Rare

Pityriasis versicolor

→ a chronic mild superficial infection of the stratum corneum

→ Causative Agent: Malassezia furfur complex ( M globosa, M restricta)

lipophilic yeast,

isolated from normal skin

and scalp

→ young adults

→Distribution: Worldwide, more common in TROPICAL climates

Pityriasis versicolorLesions:

discrete, serpentine

hyper or hypopigmented maculae on skin

Chest, upper back, arms, abdomen

Scaly, chalky , inflammation, and irritation are minimal

enlarge or coalesce

Pityriasis versicolorDiagnosis:

→ Direct microscopic examination (10-20% KOH,stained with calcofluor white)

Wood’s lamp

Pityriasis versicolorDiagnosis:

Culture is unnecessarySDA overlaid with peanut oil, olive oilDixon’s agar (glycerol-mono-oleate)

Pityriasis versicolorTreatment:

Selenium sulfide (1%) applied daily

Oral or topical azolesMild fungicides

Miconazoles

Opportunistic fungemia

→ catheter acquired infection common in neonates & adults undergoing lipid replacement therapy

→small embolic lesions in the lungs and other organs

Diagnosis: Blood drawn back from catheter, culture tip of catheter

Treatment: replace fluid and intravenous catheter

Pityriasis folliculitis

→ follicular papules and pustules

→ Back, chest, upper arms, neck, more seldom the face

→ Itchy

→ after sun exposure

Pityriasis folliculitisDiagnosis and Treatment

→ Scrapings or biopsy : yeasts at the mouths of infected follicles

→ Topical imidazole If lesions are extensive, ketoconazole, itraconazole

Prophylactic treatment 1x or 2x week to prevent relapse

Seborrheic Dermatitis

→ Host factors

→ Parkinson’s disease, AIDS

→ erythema and greasy scaling

→Scalp, face, eyebrows, ears, upper trunk

topical imidazole, ketoconazole, relapse is common

Malassezia Dermatitis

Causative Agent: Malassezia pachydermatis Phytosporum canis

Common yeast in

canine skin and external

ear canal

Microclimate alterations

host defenses are down

little zoonotic potential

Ketoconazole, miconazole

Malassezia DermatitisLesions:

Pruritus

Greasiness

Lichenification

Strong body odor

Staphylococcal pyoderma

Otitis externa

M pachydermatis from a dog ear

Peanut-shaped yeast

TINEA is Latin for “growing

worm”.

Tinea Nigra(Tinea Nigra Palmaris)

Causative Agent: Hortaea (Exophiala) werneckii

Chronic, asymptomaticsaprophyte in soil, compost, humus and

woodyoung women, warm coastal regions, tropical

Distribution: Central and South America, Australia, Southeast Asia, Africa

Tinea NigraLesions:

dark (brown to black) on palm, well demarcated macular lesions

No inflammatory reaction

Tinea NigraDiagnosis:

Direct microscopic examination (KOH)

brown to olivaceous

septate hyphae

2-celled yeastMelanized cell wall

Culture on SDA

mucoid

yeast-like

shiny black

Tinea NigraTreatment :

Whitfield’s ointment (benzoic acid compound)

2% salicylic acid, 3% sulfur

azole antifungal drugs

tincture of iodine

Miconazole nitrate, imidazoles, triazoles

PIEDRA

→ from the Spanish word stone→ fungus infection of the hair shaft

→ firm, irregular nodules→ multiple infections of the same strand

BLACK PIEDRA

Causative Agent : Piedraia hortae

Ascomycetous fungi

humans and primates

Distribution: Africa, Asia, Central, South America

can be confused with trichorrhexis nodosa and trichonodosis

soil is source of infection

BLACK PIEDRALesions:

Scalp hair

beard and moustache

axilla and groin hairs

discrete, hard, gritty , brown to black nodules

BLACK PIEDRADiagnosis & Treatment:

Direct microscopic examination (KOH)

Round to oval asci, curved to fusiform ascospores

Dark septate hyphae

Culture on SDA-CC

Very slow, dark brown to blackHeaped center with flat periphery

Short aerial mycelium

BLACK PIEDRADiagnosis & Treatment:

Usually shaving or cutting hair short

Terbinafine

WHITE PIEDRA

Causative Agent : Trichosporon beigelli, T cutaneum

Distribution : South America,AsiaN. America & Europe (sporadic)

soil, stagnant water, decaying fruit, spoiled food, sputum and body surfaces, horses

Face, axilla, genitals : commonScalp, eyebrows, eyelashes : less common

WHITE PIEDRALesions:

yellowish to white, soft, beige or greenish, irregular transparent sheath

WHITE PIEDRADiagnosis

Direct microscopic examination (10% KOH or 25% NAOH plus 5% glycerin)

Hyaline septate hyphae

Oval/rectangular arthroconidia

Blastoconidia

Culture on SDA with chloramphenicol, without cycloheximide

rapid

Cream-colored

Soft, membranous

Wrinkled radial furrows

Irregular folding

WHITE PIEDRATreatment:

Usually shaving or cutting hair short

1:200 bichloride mercury, benzoic acid & salicylic acid, 3% sulfur ointment, 2% Formalin, combinations

CUTANEOUS MYCOSES

keratinized tissue

restricted to non viable skin

unable to grow at 37° C

unable to grow in presence of serum

Host specific : keratinases, elastases, enzymes

DERMATOPHYTES

Dermatophytoses: infection of skin, hair and nails

nonviable skin: only hyphae and arthroconidia

sexual state belong to a single genus Arthroderma

GeneraPresence of

macroconidia;its

characteristicsTexture

Presence of microconidia,

its characteristics

Special name

Site of infection

Microsporum; large, spindle

shaped,multicellular form on ends of

hyphae

rough walled

“sheath of spores”

skin, hair, rare in nails

Trichophyton pencil shaped

macroconidia with blunt ends

are rare

smooth walled

“ghost hair”

Epidermophyton

only one- to five-celled,club

shaped macro are formed in

greenish-yellow colony which

mutates readily to form a sterile white growth

smooth walled x “ghost of

skin”skin and

nails, never hair

ECOLOGICAL GROUPS

GEOPHILIC : soil ; decompose keratinaceous debris

ZOOPHILIC: parasitic on animals

ANTHROPHILIC: man is exclusive host

CLINICAL MANIFESTATIONS

Tinea or ringworm – raised circular lesions

Tinea pedis : footTinea capitis: headTinea corporis: bodyTinea unguium: nails

Tinea cruris: crotch

Tinea pedis (Athlete’s foot)

Etiologic Agents: Trichophyton mentagrophytes, Trichophyton rubrum, Epidermophyton floccosum, Trichophyton interdigitale

chronic infection of the toe webs

matting or carpets with desquamated infectious scales

Tinea pedis by T rubrum (left) ; severe maceration (right)

Moccasin type by E floccosum (left) ; vesicular type by T interdigitale (right)

Tinea unguium (Onychomycosis)

Etiologic Agents: T rubrum, T interdigitale

invasion of the nail plate

one or more nails of the hands or feet

Onychomycosis : nondermatophytic fungal nail infection (yeasts)

T rubrum

Tinea corporis

Etiologic Agents: E floccosum, T rubrum, T tonsurans, M canis and M gypseum (geophilic infections)

glabrous or non hairy areas of the skin

grow within dead keratinized tissue

M canis ; after exposure to infectious kittens

Tinea cruris

Etiologic Agents: E floccosum, T rubrum, T interdigitale

proximal medial thighs, perineum and buttocks

Jock Itch - more common in males

military personnel, sharing of towels and clothing

Erythematous lesions on the thighs

Granular strain Downy strain

Tinea capitis

scalp and hair

begin at scalp with hyphal invasion

2 types: Ectothrix and Endothrix

Ectothrix Infection

around hair shaft

chain of spores imparting greenish to silvery fluorescence

Etiologic agents: M. canis, M. gypseum, T. equinum and T. verrucosum

Endothrix Infection

within hair shaft

Etiologic agents: T tonsurans, T. violaceum

black dot, weakened and break

All are anthrophilic

Kerion

Kerion: severe combined inflammatory and hypersensitivity reaction

Favus

Favus: acute inflammatory infection of hair follicle leading to scrutula or crusts

T. schoenleinii

Tinea barbae

Etiologic agents: T mentagrophytes

bearded region

zoophilic dermatophyte : pyogenic infection

Tinea manuum

Interdigital areas and palmar surfaces

Occurs almost exclusively in adults

Itchiness is moderate and minimal

Slow progress : months to years

1st pattern : ringworm pattern at dorsum of hand

2nd pattern : chronic scaling at palmar surfaceDry, hyperkeratotic, thickened, fine, silvery white scales

Tinea imbricata“Tokelau”

Etiologic agents: Trichophyton concentricum

Distribution: Southwest Polynesia, Melanesia, Southeast Asia, India, and Central America

Concentric rings; Chronic non-itchy rash

Tricophytid Reaction

hypersensitivity to metabolic products of fungus producing dermatophyids

LABORATORY DIAGNOSIS

Skin scrapings → KOH mount

Nail scrapings and clippings

Ectothrix Flouresce under Wood’s Lamp

(Bright greenish yellow)

Cuticle destroyed

Endothrix Do not flouresce

Cuticle intact

HAIR

Ectothrix Microsporum canisM. gypseumT. equinumT.verrucosum

Endothrix ALL ANTRHOPHILIC!Trichophyton tonsuransTrichophyton villaceum

Culture

Non-selective: Saboraud’s Dextrose Agar (SDA)

Selective: SDA-CC (Mycosel or Mycobiotic agar)Dermatophyte test medium

Incubation: room temperature, at least 2 weeks

Culture

SDA – CC for 1-3 weeks

Identification

Gross color & texture

Microscopic characteristics

Confirm/compare with: Written descriptions

DrawingsPhotographs

TREATMENT

Removal of infected and dead epithelial structures

Apply topical antifungal chemical or antibiotic

keep dry, avoid shared bathing facilities and infected pets

Infection Oral Topical Duration

Tinea capitis griseofulvin terbinafine

Shampoos and miconazole cream , ketoconazole, itraconazole

Weeks

Tinea corporis, Tinea pedis

itraconazole terbinafine

MiconazoleNitrateTolnaftateclotrimazole

2-4 weeks

Tinea unguium itroconazole terbinafine

---- (surgical removal)

Relapses are common

Microsporum gypseum

Geophilic

single inflammatory skin/scalp lesion

Distribution: worldwide

Flat, spreading suede-like to granular

Cinnamon growth

REVERSE

Yellow brown pigment on reverse of colony

Symmetrical, ellipsoidal

Thin-walled verrucose macroconidia

Distal end round, proximal end blunt

Trichophyton mentagrophytes

Zoophilic :mice, cats,horses,sheep,rabbits

Inflammatory skin/scalp lesions

Ectothrix infection

Distribution: worldwide

REVERSE

Flat, white to cream color, powdery to granular surface

Reverse pigment is yellowish brown to pinkish

Red brown submerged peripheral fringe

Spherical microconidia

Dense clusters, “en grappe”

Spiral hyphae

Smooth, thin-walled, clavate, multiseptate macroconidia

Trichophyton rubrum

Anthropophilic

Chronic infection of skin & nails, rarely scalp

Ectothrix and Endothrix hair infection

Distribution: worldwide

REVERSE

White, suede-like to downy

Deep wine red pigment on reverse side

Moderate to scanty slender clavate to pyriform microconidia

Macroconidia are absent,Closterospore-like projections in some strains

Trichophyton tonsurans

Variation in texture and color

Suede-like to powdery

Flat with raised center or folded

With radial grooves

Pale buff to yellow

Varying sizes and shapes of microconidia

Long clavate to pyriform

Very occasional clavate macroconidia

Partial requirement for thiamine

Trichophyton concentricum

Anthrophophilic

Tinea imbricata

Distribution:Pacific Islands of Oceania

Southeast AsiaCentral and South America

Raised and folded, glabrous and suede-like

White to cream color

Deeply folded into the agar

No microconidia and macroconidia

Trichophyton schoenleinii

Waxy and glabrous

Deeply folded honeycomb-like thallus with subsurface growth

Antler “nail head” hyphae

Favic chandeliers

No microconidia and macroconidia

Epidermophyton floccosum

Anthrophophilic

No hair invasion in vivo

Distribution: worldwide

Greenish brown or “khaki” colored

Suede-like surface, raised and folded center, flat periphery

Yellowish brown reverse pigment

White pleomorphic tufts of mycelium

Smooth thin-walled macroconidia in clusters growing directly from hyphae

No microconidia

Numerous chlamydoconidia in older cultures

Microsporum canis

Zoophilic:Cats & Dogs

Invades skin & hair, rarely nails

Distribution: worldwide

White cottony growth

Golden yellow reverse pigment

Spindle shaped, thick walled, verrucose macroconidiawith a terminal knob

Trichophyton verrucosum

Zoophilic:Cattle

Infect humans : direct contact, infected fomites

Highly inflammatory: scalp, beard,exposed areas

Ectothrix infection: flouresce only in cattles

Distribution: worldwide

Glabrous, heaped, folded white colony

No reverse pigments

Thiamine-enriched media: clavate – pyriform microconidia

Characteristic rat tail or string bean shape

END.