38 Questions
What is the name of the fungal infection that affects the nails, hair, and/or stratum corneum of the skin?
Dermatophytosis
What is the nutrient source for dermatophytes?
Keratin
What is the name of the fungus that causes infections on skin and hair?
Microsporum
What is the general name for any skin disease caused by a fungus?
Dermatomycosis
What is the category of mycoses that includes Cryptococcus neoformans, Coccidioides immitis, and Histoplasma capsulatum?
Systemic mycosis
What is the name of the fungus that causes infections on skin and nails?
Epidermophyton
Which type of dermatophyte is transmitted by human contact or infected objects?
Anthropophilic
Which of the following is NOT a characteristic of Microsporum species?
Infects hair, skin, and nail
Which of the following is a geophilic species causing human infections?
Microsporum gypseum
Which of the following is a source of ringworm infection?
Warm, damp areas
Which Trichophyton species infects the skin, hair, and nail, and infects endothrix and ectothrix?
Trichophyton rubrum
What is the characteristic of the colony of Trichophyton rubrum?
White, cottony surface and a deep red, non-diffusible pigment
Which of the following is a zoophilic species?
Microsporum canis
What is the characteristic of Microsporum canis macroconidia?
Curved or hooked tips
What is the characteristic of the macroconidia produced by Epidermophyton floccosum?
They are smooth-walled and 2-4 celled.
Which of the following is NOT a site of infection for Epidermophyton floccosum?
Hair
What is the typical location of Tinea pedis (athlete's foot)?
Between the toes or toe webs
What is the characteristic of the infected area in Tinea pedis?
It is covered by white macerated tissues.
Which of the following is a main causative dermatophyte of Tinea pedis?
T. rubrum
What is the term for ringworm infection of the groin?
Tinea cruris
Which of the following dermatophytes produces a flat, powdery colony and a reddish-brown colony when observed from the reverse side?
T. tonsurans
What is the term for ringworm infection of the scalp?
Tinea capitis
What is the term for a nail infection that may follow prolonged tinea pedis?
Tinea unguium (onychomycosis)
Which of the following is NOT a causative agent of Tinea capitis?
Epidermophyton floccosum
What is the term for a scalp infection that produces dull gray, circular patches of alopecia, scaling, and itching?
Tinea capitis (black dot)
Which of the following factors is implicated in the infection of Tinea capitis?
Crowded living conditions
What is the term for a fungal infection that involves the bearded region?
Tinea barbae (barba’s itch)
What is the term for a fungal infection that produces concentric or ring-like lesions on the skin?
Tinea corporis
Which of the following is a characteristic of Tinea cruris?
Dry, itchy lesions that often start on the scrotum and spread to the groin
What is the term for ringworm of hands or fingers?
Tinea Manus
What is the term for the allergic manifestations that may occur in the course of dermatophytosis?
Trichophytid reaction
What is the purpose of the trichophytin skin test?
To detect immediate or delayed type hypersensitivity to dermatophytic antigens
What is the primary specimen used for diagnosing dermatophytosis?
Scrapings from skin and nails, plus hairs from involved areas
What is the significance of Microsporum-infected hairs fluorescing under Wood's light?
It is a characteristic of certain fungal species
What is the purpose of using 10-20% KOH in microscopic examination?
To clear the specimen for microscopy
What is the primary goal of treatment for dermatophytosis?
To remove infected and dead epithelial structures
What is the purpose of keeping the affected area dry in the treatment of dermatophytosis?
To reduce the risk of reinfection
Which of the following antifungal agents is NOT used to treat dermatophytosis?
Amoxicillin
Study Notes
Organization of Fungal Disease
Classification of Mycoses
- Cutaneous mycoses: caused by Microsporum, Trichophyton, and Epidermophyton
- Subcutaneous mycoses: caused by Sporothrix schenkii
- Systemic mycosis: caused by Cryptococcus neoformans, Coccidioides immitis, Histoplasma capsulatum, Candida spp., and Aspergillus spp.
Cutaneous Fungal Infections
Dermatophytoses
- Also known as "ringworm" disease
- Caused by fungi called dermatophytes
- Affects the nails, hair, and stratum corneum of the skin
- Characterized by a circular, ring-like lesion with a scaly, itchy surface
Dermatophytes
- Molds that produce keratinase and use keratin as a nutrient source
- Colonize only dead layers of skin, nails, and hair
- Do not infect living tissues
- Classified into three groups: anthropophilic, zoophilic, and geophilic
Classification of Dermatophytes
- Anthropophilic: infect humans, transmitted by human contact or infected objects
- Zoophilic: infect animals, transmitted by contact with animals or their products
- Geophilic: soil fungi, transmitted to humans via exposure to soil or dusty animals
Examples of Dermatophytes
- Epidermophyton floccosum: causes skin and nail infections, globally distributed
- Trichophyton mentagrophytes: causes skin, hair, and nail infections, globally distributed
- Microsporum gypseum: causes skin and hair infections, globally distributed
- Microsporum canis: causes skin and hair infections in dogs and cats
Clinical Manifestations of Ringworm Infections
- Tinea capitis: ringworm infection of the head, scalp, eyebrows, and eyelashes
- Tinea corporis: ringworm infection of the body (smooth skin)
- Tinea cruris: ringworm infection of the groin (jock itch)
- Tinea unguium: ringworm infection of the nails
- Tinea barbae: ringworm infection of the beard
- Tinea manuum: ringworm infection of the hand
- Tinea pedis: ringworm infection of the foot (athlete's foot)
Diagnostic Laboratory Tests
- Specimens: scrapings from skin and nails, plus plucked hairs from involved areas
- Microscopic examination: detects branching hyphae or chains of spores
- Culture: Sabouraud's agar specimen incubated for 1-3 weeks at room temperature
- Identification: based on colonial morphology, microscopic morphology, and species-specific characteristics
This quiz covers the classification of mycoses, including cutaneous, subcutaneous, and systemic mycoses, as well as dermatophytoses, also known as ringworm disease.
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