Superficial Mycoses. . . . .. . . .

Superficial Mycoses andDermatophytosis

Predisposing factors: humidity Immunosuppression Poor hygiene

Affects the epidermal area with strong affinity to keratin

Superficial MycosesCausative agents:

Malassezia furfurExophiala werneckiiTrichosporon beigelii Piedraia hortae

Malassezia furfur

lipophilic yeast Found as a normal flora on the skinDiseases :

Pityriasis versicolor Pityriasis folliculitis Seborrhoeic dermatitis; Dandruff Systemic infection

Major Clinical Manifestation:

Hyper- or hypopigmented of the skin. Lesions are well-demarcated (white,

pink or brownish) Fawn-colored macules are the most

common presentation Trunk and upper arms Rarely on neck and face

http://dermnetnz.org/common/image.php?path=/fungal/img/pitver4.jpg

Pityriasis folliculitis

follicular papules and pustules back, chest and upper armssometimes the neck, seldom the face

Itchy and often appear after sun exposure

Pityriasis folliculitis

Seborrhoeic dermatitis

changes in quantity and composition of sebum increase in wax esters shift from triglycerides to shorter

fatty acid chains increase in alkalinity of skin external local factors such as occlusion

Clinical manifestations:

erythema and scaling in areas with a rich supply of sebaceous glands scalp, face, eyebrows, ears and upper

trunk Lesions are covered with greasy scales Itching is common in the scalp

13

Systemic Infection (M. furfur)

common among infants as catheter acquired Intravenous infusions of lipid Pneumonia results from emboli from

the infected IV catheter

Clinical material/Specimen: Skin scrapings blood indwelling catheter tips

Laboratory Diagnosis

1. Direct Microscopy

10% KOH (glycerol w/ Parker ink or Calcofluor white) clusters of thick-walled round

budding yeast-like cells short angular hyphal forms Yeast cells (3-7um)

Laboratory Diagnosis

“Spaghetti and meatballs”

“Spaghetti and meatballs”

GMS

KOH w/ PI

2. Culture For systemic infection Stimulate growth by natural oils or

other fatty substances Sabouraud's dextrose agar or Sheep

blood agar containing Acti-Dione Dixon's agar containing glycerol mono-

oleate20

Laboratory Diagnosis

Malassezia furfur

Colonies of Malassezia furfur on Dixon's agar. A specialized isolation medium containing glycerol-mono-oleate

Microscopic apperances: Broad-based buds The collarettes of the phialides appear

as distinct dark rings separation the mother & daughter cells

currently no commercially available Serology

Laboratory Diagnosis

Management and Treatment:1. topical agent: imidazole

Ketoconazole shampoo

2. Oral treatment : ketoconazole : itraconazole

3. Alternative: zinc pyrithione shampoo selenium sulfide lotion propylene glycol 50% in water twice

daily

Helpful Features

White discoloration of skin or light brown discoloration

Spaghetti and meatballs

Oil and FA requirement

Exophiala wernekii

Phaeoannellomyces werneckiiCladosporum werneckii

common saprophytic fungus soil, compost, humus and on wood

Exophiala werneckiiDisease: Tinea nigra

Chronic superficial fungal infection of the palms

brown to black macules (palmar and plantar and other surfaces of the skin)

Well-defined dark patch with irregular margin, 1-5 cm in diameter on palm; “stained appearance”

Tinea nigra

Lesions: non-inflammatory and non-scaling

Both tropics and temperate zones Usually <20 y/o; > females (3:1) Predisposing factor: excessive sweating

Exophiala werneckii

Clinical Material: Skin scrapings1. Direct Microscopy:

10% KOH and Parker ink; calcofluor white mounts.

2. Culture: Primary isolation media

Sabouraud's dextrose agar

Laboratory Diagnosis

pigmented brown to dark (dematiaceous)septate hyphal elements

2-celled yeast cells

Initially colonies are mucoid, yeast-like and shiny black. (young yeast)

Abundant aerial mycelia and become velvety, dark olivaceous in colour. (mature mould)

Exophiala werneckii

Serology Not required for diagnosis

Management & Treatment:

Sulfur soap, SSA, azoles Topical treatment

Whitfield's ointment (benzoic acid compound)

Imidazole agent twice a day for 3-4 weeks

33

Piedraia hortae ascomycetous fungus common in Central and South America

and South-East Asia Disease: Black piedra

Chronic fungal infection of the hair shaft mostly affects young adults epidemics in families

Clinical Manifestations: Does not penetrate the hair follicle Scalp hair: rough, sandy Infected hairs: hard black nodules on

the shaft Nodules: hard, fusiform, firmly

attached to hair shaft

Piedraia hortae Black piedra

Clinical Manifestations: Thick part: fungal cells cemented

together Thin part: hyphal elements

Piedraia hortae Black piedra

Black piedra

Clinical Material: hairs with hard black nodules

1. Direct Microscopy: 10% KOH w/ Parker ink; calcofluor white

darkly pigmented nodules: hair shaft Nodules: pigmented center containing

asci

Laboratory Diagnosis

2. Culture:

primary isolation media Colonies are dark, brown-

black Take about

2-3 weeks to appear

Laboratory Diagnosis

Management and Treament:

shave or cut the hairs short Terbinafine

Dose: 250 mg a day for 6 weeks

Trichosporon beigelii

Worldwide, tropical or subtropical regions

More in temperate zones Disease: White piedra

superficial cosmetic fungal infection of the hair shaft

Affects scalp, axilla, facial and genital hair

Trichosporon beigelii White piedra

Clinical Manifestations: common in young adults Nodules: mucilaginous, white, follicles

not affected irregular, soft, white or light brown

nodules firmly adhering to the hairs 1.0 - 1.5 mm in length no pathological changes are elicited

White piedra

1. Direct Microscopy: 10% KOH and Parker ink; calcofluor white

Laboratory Diagnosis

2. Culture:

primary isolation media white or yellowish to deep cream

colored smooth, wrinkled, velvety, dull

colonies with a mycelial fringe.

Laboratory Diagnosis

Serological test in not Required

Management and Treatment:

Shave the hairs Topical: imidazole agent

Trichosporon beigelii

Superficial Mycoses

Causative agents:

Malassezia furfurExophiala werneckiiTrichosporon beigelii Piedraia hortae

B. Dermatophytes(Cutaneous mycoses)

- fungal infections involving the dermis and its appendages (hair follicles and nails)

o Dermatophytosis - "ringworm" disease (mycotic infection) of the nails, hair, and/or stratum corneum of the skin caused by fungi called dermatophytes.

o Dermatomycosis - more general name for any skin disease caused by a fungus. - invasion of the cutaneous tissues by other fungi.

THE SKIN PLANTS Etiological agents are called dermatophytes - "skin

plants". Three important anamorphic genera, (i.e., Microsporum, Trichophyton, and Epidermophyton), are involved in ringworm.

Dermatophytes are keratinophilic - "keratin loving". Keratin is a major protein found in horns, hooves, nails, hair, and skin.

- use keratin as a source of nitrogen Ringworm - disease called ‘herpes' by the Greeks,

and by the Romans ‘tinea' (which means small insect larvae).

Infections by Dermatophytes Severity of ringworm disease depends on (1)

strains or species of fungus involved and (2) sensitivity of the host to a particular pathogenic fungus.

More severe reactions occur when a dermatophyte crosses non-host lines (e.g., from an animal species to man).

Dermatophytes Common Causative agents:a. Microsporum

- hair, skin, rarely nails - children, rarely in adults- spontaneous remission

b. Trichophyton - hair, skin & nails- both children & adults- chronic.

c. Epidermophyton - skin, nails, rarely hair- adults, rarely children

Among dermatophytes there appears to be a evolutionary transition from a saprophytic to a parasitic lifestyle.

Geophilic species - keratin-utilizing soil saprophytes (e.g., M. gypseum, T. ajelloi).

Zoophilic species - keratin-utilizing on hosts - living animals (e.g., M. canis, T. verrucosum).

Anthropophilic species - keratin-utilizing on hosts - humans (e.g., M. audounii, T. tonsurans)

Common Dermatomycoses Diseases:

Hairy areas: Tinea capitis Tinea barbae

Skin: Tinea corpuris Tinea cruris Tinea manum Tinea pedis Tinea fascie Tinea imbricata

Nail: Tinea ungium

Microsporum species

Microsporum gypseumMicrosporum canis

Microsporum speciesCommon features: Colony:

Mycelium: white to buff Underside: yellow to reddish brown

Microscopic attached singly thick walls & mature forms are echinulate (spiny) Spindle-shaped macroconidia Septate hyaline hyphae

Microsporum gypseum complex Teleomorphs are Arthroderma gypseum and A. incurvatum.

Produces abundant macroconidia brownish-yellow due to large numbers macroconidia.

Surface of culture colony often is powdery in appearance.

Reverse of colony often appears ragged around edges.

Macroconidia usually have 4-6 septa or crosswalls, up to 40 µm long

Microconidia are smaller than in M. canis.

In lactophenol, water is extracted and can cause the macroconidia walls to collapse. This is an artifact due to mounting media. Macroconidia do not form on infected hair!

Microsporum gypseumMicrosporum gypseum

Microsporum canis Teleomorph is an ascomycete called

Arthroderma otae.

Macroconidia are abundant, thick-walled with many septa, up to 15. Macroconidia are often hooked or curved at ends.

Microconidia are small and clavate (club-shaped).

Microsporum canisTeleomorph: Arthroderma otaeMicrosporum canisTeleomorph: Arthroderma otae

Dermatophytosis of the skin Clinical Manifestations: “ringworm” Papules to pustules with clear center and active

borders (peripheral pustules and scaling), itchy,circinate and serpiginous with inflammatory, vesicular, enlarging margins

Differential Diagnosis: Psoriasis: dry and circinate borders Ezcema: no clear center

Tinea or “ringworm”: basic lesion

Dermatophytosis (skin and nail)

Tinea fascie (face) Tinea imbricata (subtype of Tinea corpuris,

concentric layers of lesions) Tinea cruris (inguinal area) Tinea pedis (interdigits of the feet) Tinea manum (interdigits of the hand) Tinea ungium (fingernails)

Tinea fascies

Tinea corporis

Tinea manum (hand)

Tinea pedis (feet)

Tinea imbricata

Tinea unguium

Epidermophyton species

Epidermophyton floccosum

Epidermophyton floccosum

Only one pathogenic species in this genus.

Tinea unguium and tinea cruris are often caused by this fungus.

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Epidermophyton floccosumColony:

Mycelium: yellow – green, “khaki”; suede, gentle folds; slow grower

Underside: green to brown

Epidermophyton floccosum Microscopic:

attached in multiples (2 – 4/group) moderately thick , smooth walls (beaver tails) Clubbed-shaped, 2 – 5 cell macroconidia Septate,hyaline hyphae

Chlamydoconidia Typically present particularly in older culture.

Dermatophytes

Epidermophyton floccosum

Areas affected: skin and nails Disease: Tinea cruris or “jock itch”

Often start on the scrotum and spread to the groin as dry, itchy lesions

Source of infection: Sharing of linens, towels or clothes Athletes, soldiers, ship crews

Tinea cruris (groin) – jock itch

Trichophyton species

The word "trichophyton" literally means "hair plant". Presence of macroconidia in cultures varies and may not help

in identification of cultures. Most common species include:

Trichophyton mentagrophytes T. rubrum T. tonsurans T. verrucosum T. violaceum T. schoenleinii T. ajelloi (rare infects humans).

ON SKIN: Scrapings from skin and nails cannot distinguish species in this genus.

ON HAIR: Pattern of infection can help distinguish etiologic or causal agent.

For Microsporum species - infections on hair lead to a mosaic pattern of arthrospores.

For Trichophyton species - infections on hair follow one of the 4 patterns.

Ectothrix - more or less parallel rows of arthrospores produced on surface of hair. 1. Small-spored ectothrix (arthrospores are < 5 mm in

diameter) - caused by T. mentagrophytes or T. rubrum (rare). Spores are about the same size as those produced by Aspergillus.

2. Large-spored ectothrix (arthrospores are 5- 10 mm in diameter) - caused by T. verrucosum.

Endothrix - growth inside hair shaft only! 3. "Black-dot" endothrix (hair stubs filled with

arthrospores) - caused by T. tonsurans or T. violaceum. 4. "Favus hair" endothrix (honeycomb pattern of damage

seen on surface of hair shaft) - caused by T. schoenleinii.

Trichophyton species

Common Features: Colony:

Mycelia: Cream, buff to brown, granular to wrinkled Underside: differ (brown to red)

Microscopic feature Microconidia; oval- pyriform attached singly, some in clusters have smooth walls Hyaline septate hyphae

Areas affected: hair, skin and nails

Trichophyton rubrum- spores spherical/elongate

Ectothrix (Trichophyton rubrum)

Trichophyton mentagrophytes

Growth rate: moderate

Texture: deep, cottony

Thallus color: white

Reverse: pale yellow to tan

Trichophyton mentagrophytes- spores are pyriform

round microconidia in grape-like clusters

(“ën grappe”) spiral hyphae

Endothrix

Other Biochemical Tests for T. mentagrophytes

Urease: positive

Vitamin requirement: none

Hair perforation: positive

Tinea capitis (head, hair) Clinical Manifestations:

Bald patches, moist, itchy, scaly Papules to pustules Friable hair

Differential Dx: Alopecia: no scaling Psoriasis: no loss of hair; silvery scaling Seborrheic dermatitis: diffuse hair loss; 6-8 months old; pustular

Other hairy areas:Tinea barbei (beard)

Tinea capitis

Differential Diagnoses:Alopecia areata

Differential Diagnoses:Psoriasis

Differential Diagnoses:Seborrheic keratosis

Tinea barbei

Other Forms Superficial Mycoses

KeratomycosisOnychomycosisCutaneous candidiasis

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