MLS 314 Cutaneous mycoses Flashcards by Arriane Camacho

Involves deeper layers of the skin

CUTANEOUS MYCOSES

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→ moderate to intense inflammatory reaction

CUTANEOUS MYCOSES

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2 Types of CUTANEOUS MYCOSES

Dermatomycoses
Dermatophytoses

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Caused by fungi other than the dermatophytes

Dermatomycoses

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Involves only the skin

Dermatomycoses

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Caused by dermatophytes

Dermatophytoses

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“True cutaneous mycoses”

Dermatophytoses

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May involve the skin, hair, & nails

Dermatophytoses

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Other names
o “Buni”
o Ringworm
o Tinea

DERMATOPHYTOSES

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Characteristic lesion: Circular & expanding inflammatory region

DERMATOPHYTOSES

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Causative agent: Dermatophytes
o “Plants of the skin”
o Keratinophilic fungi: Production of keratinase

DERMATOPHYTOSES

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Arthroderma (Nannizia)
Skin and hair

Microsporum

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Arthroderma
Skin, hair, and nails

Trichophyton

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None
Skin and nails

Epidermophyton

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Microsporum audouinii
Trichophyton mentagrophytes var interdigitale
Trichophyton rubrum
Trichophyton tonsurans
Trichophyton concentricum
Trichophyton schoenleinii
Trichophyton violaceum
Epidermophyton floccosum

Anthropophilic

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Microsporum canis
Trichophyton mentagrophytes var mentagrophytes
Trichophyton verrucosum

Zoophilic

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Microsporum gypseum

Geophilic

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2 Clinical classification of DERMATOPHYTOSES:

Skin and Nail Infections
Hair Infection Types

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▪ Trunk and limbs; Shoulder, neck region, and arms

Tinea corporis

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▪ Causative agents: M. canis, T. mentagrophytes, T. rubrum, T. tonsurans

Tinea corporis

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▪ Areas adjacent to scalp, eyebrows, eyelashes

Tinea capitis

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▪ Causative agents: Microsporum, Trichophyton

Tinea capitis

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▪ “Barber’s itch”

Tinea barbae

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▪ Bearded area, neck

Tinea barbae

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▪ Causative agents: T. mentagrophytes, T. verrucosum, T. schoenleinii

Tinea barbae

▪ “Jock Itch”

Tinea cruris

▪ Groin, inner thighs, buttocks

Tinea cruris

▪ Causative agents: T. rubrum, T. mentagrophytes, E. floccosum

Tinea cruris

▪ Feet ; “Athlete’s foot”

Tinea pedis

▪ Causative agents: T. rubrum, T. mentagrophytes var interdigitale, E. floccosum

Tinea pedis

▪ Hands

Tinea manuum

▪ Causative agents: M. canis, T. mentagrophytes var interdigitale, T. rubrum, T. tonsurans

Tinea manuum

Onychomycosis

Tinea unguium

▪ Nails

Tinea unguium

▪ Causative agents: T. mentagrophytes , T. rubrum, T. schoenleinii, T. violaceum, E. floccosum

Tinea unguium

▪ Specialized form of tinea corporis

Tinea imbricata

▪ Ring-like growth in overlapping patterns/ circles

Tinea imbricata

▪ Causative agents: T. concentricum

Tinea imbricata

▪ Growth of fungal elements on the outer part of the hair shaft

Ectothrix infection

▪ Causative agents o Trichophyton mentagrophytes o Trichophyton verrucosum o Microsporum audouinii

Ectothrix infection

▪ Hyphae → fragment to individual cells → development of arthroconidia

Ectothrix infection

▪ Can destroy hair cuticle

Ectothrix infection

▪ M. audouinii: Hair becomes gray on color and breaks off → grayish patch in the scalp → “GRAY-PATCH” Tinea capitis

Ectothrix infection

▪ Causative agents o Trichophyton tonsurans o Trichophyton violaceum

Endothrix

▪ Growth of fungal elements inside the hair shaft

Endothrix

▪ Development of arthroconidia; Does not usually destroy the cuticle

Endothrix

▪ Hair becomes brittle → breaks off just above the surface of the scalp → “BLACK DOT” Tinea capitis

Endothrix

▪ Causative agent: T. schoenleinii

Favic type

▪ Hyphae within the hair shaft → growth of hyphae parallel to the hair shaft→ degeneration of hyphae → tunnels within hair shaft

Favic type

▪ No development of arthroconidia

Favic type

▪ Severe form: Scutula o Yellowish, circular lesions with a characteristic “mousy” odor

Favic type

▪ Hypersensitivity reaction to dermatophytic infection elsewhere in the body

Dermatophytid reaction

Specimens of CUTANEOUS MYCOSES

▪ Skin scrapings ▪ Hair ▪ Nail clippings

Exposure to Wood’s Light

CUTANEOUS MYCOSES

- Hyphae o Small: 2-3 microns o Hyaline, septate, branching

KOH Preparation

- Presence of arthroconidia: Endothrix and ectothrix infection vs Faciv type

KOH Preparation

- Branching, sometimes fluorescing hyphae

Calcofluor white staining

- Disadvantage of not being able to inhibit growth of saprophytic fungi

Nonselective SDA

- Incubation: 25-300C for 1-3 weeks

Nonselective SDA

- Selective SDA

Mycosel/ Mycobiotic

- Incorporation of antimicrobial agents

Mycosel/ Mycobiotic

- Incubation: 25-300C for 1-3 weeks

Mycosel/ Mycobiotic

2 antimicrobial agents

Chloramphenicol Cycloheximide

: Inhibits growth of bacteria

Chloramphenicol

: Inhibits growth of saprophytic fungi

Cycloheximide

2 Dermatophyte test medium

Selective for dermatophytes Differential for dermatophytes

o Incorporation of cycloheximide, chlortetracycline, and gentamicin

Selective for dermatophytes

o Incorporation of phenol red: Dermatophytes →alkaline products → reddish discoloration of agar

Differential for dermatophytes

2 Clues for Identification

i. Colonial characteristics ii. Microscopic characteristics

▪ Growth rate

Colonial characteristics

▪ Pigmentation o Obverse side o Reverse side

Colonial characteristics

▪ Texture and topography

Colonial characteristics

▪ Conidiation o Macroconidia o Microconidia

Microscopic characteristics

Anthropophilic

Microsporum audouinii Trichophyton mentagrophytes Type II Trichophyton mentagrophytes var interdigitale Trichophyton rubrum Trichophyton tonsurans Trichophyton concentricum Trichophyton schoenleinii Trichophyton violaceum Epidermophyton floccosum

Zoophilic

Microsporum canis Trichophyton mentagrophytes Type I Trichophyton mentagrophytes var mentagrophytes Trichophyton verrucosum

Geophilic

Microsporum gypseum

Intermediate to slow growth

Microsporum audouinii Trichophyton tonsurans

Rapid growth

Microsporum canis Microsporum gypseum

Intermediate growth

Trichophyton mentagrophytes Type I Trichophyton mentagrophytes var mentagrophytes Trichophyton mentagrophytes Type II Trichophyton mentagrophytes var interdigitale Epidermophyton floccosum

Slow growth

Trichophyton rubrum Trichophyton concentricum Trichophyton schoenleinii Trichophyton violaceum

Slow growth Improved at 370C

Trichophyton verrucosum

Pigmentation: Obverse: Light Reverse: Pale salmon to pale brownish

Microsporum audouinii

Flat and velvety

Microsporum audouinii

Pigmentation: Obverse: White to buff Reverse: Yellow (rarely pale)

Microsporum canis

Cottony to granular

Microsporum canis

Pigmentation: Obverse: cinnamon-colored Reverse: light tan

Microsporum gypseum

Flat and granular

Microsporum gypseum

Pigmentation: Obverse: yellow cream to buff or white Reverse: pale to red brown

Flat and granular to powdery

Trichophyton mentagrophytes Type I Trichophyton mentagrophytes var mentagrophytes

Pigmentation: Obverse: yellow cream to buff or white Reverse: pale to red brown

Trichophyton mentagrophytes Type II Trichophyton mentagrophytes var interdigitale

Flat and powdery to cottony

Trichophyton mentagrophytes Type II Trichophyton mentagrophytes var interdigitale

Type I Pigmentation: Obverse: White to reddish Reverse: Wine-red (occasionally yellow)

Trichophyton rubrum

Type I Cottony to velvety

Trichophyton rubrum

Type I Cottony to velvety

Trichophyton rubrum

Type II Pigmentation: Obverse: cream to deep red Reverse: wine-red

Trichophyton rubrum

Type II Powdery to low velvety

Trichophyton rubrum

Pigmentation: Obverse: yellow Reverse: yellow-brown to chestnut-red-brown

Trichophyton tonsurans

Flat and velvety to powdery

Trichophyton tonsurans

Pigmentation: Obverse: white that becomes honey-brown Reverse: yellow

Trichophyton concentricum

Folded and furrowed

Trichophyton concentricum

Pigmentation: Obverse: white or cream Reverse: colorless or salmon

Trichophyton verrucosum

Commonly small Convoluted with raised center and flat periphery Submerged growth Glabrous to slightly velvety

Trichophyton verrucosum

Pigmentation: Obverse: white to tan Reverse: colorless or light yellow

Convoluted to folded and glabrous to slightly velvety

Trichophyton schoenleinii

Often submerged into the surrounding medium

Trichophyton schoenleinii

“Mousy” odor typically develops in cultures

Trichophyton schoenleinii

Pigmentation: Obverse & reverse: Initially cream then becoming lavender or purple

Trichophyton violaceum

Verrucose and glabrous

Trichophyton violaceum

Pigmentation: Obverse: White that tends to turn khaki green-brown, center is folded Reverse: Yellow-brown with observable folds

Epidermophyton floccosum

Flat, slightly granular at first

Epidermophyton floccosum

Conidia: Absent, bizarre if present

Microsporum audouinii

Hyphae: Atypical vegetative pectinate hyphae with terminal chlamydospores

Microsporum audouinii

Macroconidia: 6-15 cells; Assymetrical beak apex; Abundant, spindle-shaped with thick, rough walls

Microsporum canis

Microconidia: Clavate or pyriform, laterally attached to hyphae

Microsporum canis

Hyphae: Hyaline, septate, branching

Microsporum canis

Macroconidia: 3-9 celled, broadly spindleshaped, rough-walled; Terminal ends may be rounded

Microsporum gypseum

Microconidia: If present, single or in small clusters

Microsporum gypseum

More conidia when compared to Type II

Trichophyton mentagrophytes Type I Trichophyton mentagrophytes var mentagrophytes

Macroconidia: uncommon, cigar-or pencilshaped with thin, smooth walls, 3-6 cells

Trichophyton mentagrophytes Type I Trichophyton mentagrophytes var mentagrophytes

Microconidia: Type I: Unicellular, arranged singly along the hyphae on short pedicles or “en grappe”

Trichophyton mentagrophytes Type I Trichophyton mentagrophytes var mentagrophytes Trichophyton mentagrophytes Type II Trichophyton mentagrophytes var interdigitale

Type II: Clavate or pyriform-shaped arranged singly in sleeves en thryses along the hyphae by pedicles

Trichophyton mentagrophytes Type I Trichophyton mentagrophytes var mentagrophytes Trichophyton mentagrophytes Type II Trichophyton mentagrophytes var interdigitale

Hyphae: Hyaline, septate, and branched; spiral form in 30% of isolates

Trichophyton mentagrophytes Type I Trichophyton mentagrophytes var mentagrophytes Trichophyton mentagrophytes Type II Trichophyton mentagrophytes var interdigitale

More conidia in Type II than in Type I

Trichophyton rubrum

Macroconidia are few, smooth-walled, pencilshaped, attached directly to the hyphae

Trichophyton rubrum

Microconidia are tear-shaped, single, and lateral along the hyphae

Trichophyton rubrum

Abundant wine-red, water-soluble pigment

Trichophyton rubrum

Macroconidia are absent or rare, distorted

Many microconidia of various size and shapes with flattened base “Balloon forms” – aged pleomorphic microconidia

Trichophyton tonsurans

Macroconidia and microconidia are rare

Trichophyton concentricum

Masses of tangled hyphae, presence of chlamydospores

Trichophyton concentricum

Macroconidia are rare, 3-5 cells, thin-walled, “RAT-TAIL”

Trichophyton verrucosum

Microconidia are large, clavate, and lateral

Trichophyton verrucosum

No conidia produced

Hyphae: Hyaline and septate “Favic chandeliers”, “antlers”, or “nailhead”

Trichophyton schoenleinii

Hyphae: Hyaline and septate “Favic chandeliers”, “antlers”, or “nailhead”

Trichophyton schoenleinii

Absent conidia

Trichophyton violaceum

Swollen hyphae containing cytoplasmic granules

Trichophyton violaceum

Macroconidia: “Snowshoes”, “paddles”, or “beaver’s tail” Large, multicelled, club-shaped, smooth-walled macroconidia, single or in clusters of 2-3 Microconidia is not formed

Epidermophyton floccosum A

Physiological tests

a. Polished rice test b. Hair perforation test c. Urease test d. Growth factor test

a. Polished rice test (+) (-)

(+) M. canis (-) M. audouinii

b. Hair perforation test (+) (-)

(+) T. mentagrophytes o M. canis o M. gypseum o T. tonsurans o T. violaceum (-) T. rubrum

c. Urease test (+) (-)

(+) T. mentagrophytes (-) T. rubrum

d. Growth factor test (+) (-)

(+) T. verrucosum (-) T. violaceum

b. Hair perforation test (+) (-)

(+) Wedge-shaped perforation into the hair (-) No perforation

c. Urease test (+) (-)

(+) Red to purple color in less than 4 days of incubation (-) No color change

d. Growth factor test (+) T. verrucosum (-) T. violaceum

(+) Positive growth in the presence of inositol (-) Positive growth in the presence of inositol & thiamine

Polished rice test - Procedure: o Medium: (?) o Transfer colonies from (?) o Incubation: (?) (?) (?)

Rice grains with distilled H2O primary isolation medium ▪ Room temperature ▪ 6-10 days ▪ 25-300C

Hair perforation test Procedure: o Culture medium: (?) o Add (?) o Juvenile hair (?( o Incubate up to (?)

Yeast extract in distilled water strands of hair (< 1 cm) 4 weeks at room temperature

Urease test Culture medium:

o Christensen’s agar o Stuart’s broth

Growth factor test Casamino acid agar/ Trichophyton agar

o Nicotinic acid o L-Histidine o Growth factors ▪ Thiamine ▪ Inositol