Dermatophytes and Dermatophytosis

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Questions and Answers

What is the primary site of infection in Sporotrichosis?

Hands and upper extremities

Scalp

Face

Feet and lower extremities (correct)

What is the characteristic of fungi in Phaeohyphomycosis?

Fungal elements are brown pigmented (correct)

Fungal growth is rapid

Fungal growth is inhibited at 25°C

Hyphae are septate

Which of the following is a diagnostic method for Sporotrichosis?

Direct microscopic examination (correct)

Tissue biopsy with special stains

Blood culture

Serum agglutination test

What is the term for a fungal infection of the skin, hair, or nails?

Dermatomycosis Signup and view all the answers

What is the characteristic of the colonies of Sporothrix schenckii in Sabouraud's dextrose agar?

Black and shiny Signup and view all the answers

Which of the following is a treatment option for Sporotrichosis?

Combining miconazole and surgery Signup and view all the answers

Which type of dermatophytosis is commonly found in children?

Tinea capitis Signup and view all the answers

What is the name of the dermatophytosis that affects the bearded areas of the face and neck?

Tinea barbae Signup and view all the answers

Which of the following is NOT a type of dermatophytosis?

Sporotrichosis Signup and view all the answers

What is the term for the ringworm infection of the skin and hair?

Tinea corporis Signup and view all the answers

Which of the following is NOT a characteristic of dermatophytosis?

Infection of the deeper layers of the skin Signup and view all the answers

What is the term for the dermatophytosis that affects the nails?

Tinea unguium Signup and view all the answers

What is the primary mode of infection for Mycetoma?

Trauma to the skin by plant materials Signup and view all the answers

Which of the following is a common symptom of Histoplasmosis?

Chest pain Signup and view all the answers

What is the primary site of infection for Coccidioidomycosis?

Lungs Signup and view all the answers

Which of the following fungi can cause skin and bone infections?

H. capsulatum var. duboisii Signup and view all the answers

What is the name of the disease caused by Paracoccidioides brasiliensis?

South American blastomycosis Signup and view all the answers

Which of the following is a manifestation of hypersensitivity to Coccidioides immitis antigens?

Erythema nodosum Signup and view all the answers

What is the name of the fungi that causes Mycetoma?

Eumycetoma Signup and view all the answers

What is the diagnosis method for Tinea Nigra?

Microscopic examination of skin scrapings Signup and view all the answers

What is the treatment for dermatophytosis?

Topical azoles or selenium sulfide shampoo Signup and view all the answers

What is the causative agent of Tinea Nigra?

Hortaea werneckii Signup and view all the answers

What is the characteristic appearance of Tinea Nigra?

Irregular, pigmented (brown to black) macule Signup and view all the answers

Which of the following is NOT a type of opportunistic mycoses?

Dermatophytosis Signup and view all the answers

What is the typical location of Tinea Nigra?

Palms or soles Signup and view all the answers

Study Notes

Dermatophytes

3 Genera: Trichophyton, Microsporum, and Epidermophyton
Keratinophilic and keratinolytic, invade only the upper outermost layer of the epidermis (stratum corneum)
Infections:
- Trichophyton: skin, hair, and nails
- Microsporum: skin and hair
- Epidermophyton: skin and nails

Dermatophytosis

Infection named according to anatomic location involved
Types of infections:
- Tinea corporis: small lesions on the body
- Tinea barbae: ringworm of the bearded areas of the face and neck
- Tinea pedis: athlete's foot, infection of toe webs and soles of feet
- Tinea unguium (onychomycosis): infection of the nails
- Tinea capitis: infection of the head, frequently found in children

Ecology of Dermatophytes

Source of infection:
- Anthropophilic: person-to-person transmission through contaminated objects
- Zoophilic: associated with animals, direct transmission to humans through close contact
- Geophilic: usually found in soil, transmitted to humans through direct exposure

Laboratory Diagnosis

Demonstration of fungal hyphae by direct microscopy of skin, hair, or nail samples
Isolation of organisms in culture

Treatment

Thorough removal of infected and dead epithelial structures
Application of topical antifungal chemicals
Prevention of reinfection: keep the area dry, avoid sources of infection (e.g., infected animals or shared bathing facilities)

Superficial Mycoses

Colonize the keratinized outer layers of the skin, hair, and nails
Asymptomatic, mostly a cosmetic concern
Examples:
- Pityriasis (Tinea) Versicolor
- Tinea Nigra
- White Piedra
- Black Piedra

Pityriasis (Tinea) Versicolor

Causative agent: Malassezia furfur
Lesions: small, hypopigmented or hyperpigmented macules
Clinical findings:
- Site: feet, lower extremities, hands
- Findings: abscess formation, draining sinuses containing granules, deformities
- Dissemination: muscles and bones

Sporotrichosis

Causative agent: Sporothrix schenckii
Initial lesion: granulomatous nodule that will ulcerate and become necrotic
Multiple subcutaneous nodules occur along the lymphatic vessels

Phaeohyphomycosis

Cutaneous phaeohyphomycosis: characterized by the presence of brown pigmented fungal elements
Fungi: usually pigmented dark brown
Infections: may become invasive and systemic (invading various organs)

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Description

Learn about dermatophytes, fungi that cause skin, hair, and nail infections, and dermatophytosis, the infection caused by these fungi.