Fungal Skin Infections Overview
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Questions and Answers

What type of fungi is characterized as unicellular and thrives at 37°C?

  • Mold
  • Dimorphic fungi
  • Dermatophytes
  • Yeast (correct)

    • Which of the following describes the general transmission route of zoophilic dermatophytes?

  • Primarily from animals to humans (correct)
  • From humans to animals
  • From soil to humans
  • From plants to humans

    • What distinguishes dermatophytes from the other types of fungi mentioned?

  • They only affect animals.
  • They are unicellular fungi.
  • They can produce spores in soil.
  • They infect keratinized structures. (correct)

    • Which of the following is NOT a type of tinea caused by dermatophytes?

    <p>Tinea auris</p> Signup and view all the answers

    What is the characteristic appearance of a lesion in tinea corporis?

    <p>Central clearing with raised edges</p> Signup and view all the answers

    Which clinical variant of tinea corporis is usually associated with contact sports?

    <p>Tinea gladiatorum</p> Signup and view all the answers

    What effect do topical steroids have on tinea incognito lesions?

    <p>They change the morphology of the lesions.</p> Signup and view all the answers

    Which of the following dermatophytes is commonly associated with infections following contact with infected kittens?

    <p>Microsporum canis</p> Signup and view all the answers

    What is the primary site of infection for tinea cruris?

    <p>Groin</p> Signup and view all the answers

    Which of the following is a characteristic symptom of kerion?

    <p>Boggy swelling on the scalp</p> Signup and view all the answers

    Tinea capitis can have non-inflammatory variants. Which of the following describes the grey patch variant?

    <p>Multiple round patches with scaly white scalp</p> Signup and view all the answers

    Which predisposing factor is particularly associated with tinea cruris?

    <p>Moist weather</p> Signup and view all the answers

    What is the primary cause of dermatophytid reactions?

    <p>Systemic response to fungal antigens</p> Signup and view all the answers

    What is a common symptom of tinea pedis?

    <p>Scaling and maceration between the toes</p> Signup and view all the answers

    What type of fungi primarily causes tinea cruris?

    <p>Anthropophilic fungi</p> Signup and view all the answers

    Which type of tinea is primarily associated with exposure to animals?

    <p>Tinea barbae</p> Signup and view all the answers

    What is a common presentation of hyperkeratotic tinea pedis?

    <p>Scaling of the planter surface and sides of feet</p> Signup and view all the answers

    Which type of tinea unguium is typically associated with crumbling of the nail's free edge?

    <p>Distal and lateral subungual onychomycosis</p> Signup and view all the answers

    What complication can arise from fierce animal ringworm of the scalp?

    <p>Permanent scarring alopecia</p> Signup and view all the answers

    What is a characteristic method for diagnosing fungal infections of the scalp?

    <p>Wood’s light examination revealing green fluorescence</p> Signup and view all the answers

    What factor contributes to the transmission of tinea pedis?

    <p>Desquamated skin scales in carpets and matting</p> Signup and view all the answers

    Which of these is NOT typically a differential diagnosis for tinea pedis?

    <p>Alopecia areata</p> Signup and view all the answers

    Which is a common treatment for localized tinea infections?

    <p>Imidazole preparations</p> Signup and view all the answers

    What symptom is associated with vesiculobullous tinea pedis caused by T. mentagrophytes?

    <p>Pruritic tense vesicles and bullae</p> Signup and view all the answers

    What is the primary characteristic of candidiasis in mucous membranes?

    <p>Fungal infection leading to lesions</p> Signup and view all the answers

    What does a KOH mount reveal in cases of candidiasis?

    <p>Budding yeast and pseudohyphae</p> Signup and view all the answers

    Which of the following is NOT a common site for cutaneous candidiasis?

    <p>Forehead</p> Signup and view all the answers

    What is one effective treatment for oral candidiasis?

    <p>Oral suspensions of nystatin</p> Signup and view all the answers

    What is the primary action of flucytosine in antifungal therapy?

    <p>Disruption of nucleic acid synthesis</p> Signup and view all the answers

    Which of the following is a common predisposing factor for candidiasis?

    <p>High humidity and occlusive clothes</p> Signup and view all the answers

    Which antifungal class is known for inhibiting squalene epoxidase?

    <p>Allylamines</p> Signup and view all the answers

    What is a recommended action for patients with chronic paronychia?

    <p>Keep hands warm and dry</p> Signup and view all the answers

    What is the most common location for lesions in Pityriasis (Tinea) Versicolor?

    <p>Back and upper arms</p> Signup and view all the answers

    Which treatment is specifically indicated for Tinea Corporis?

    <p>Griseofulvin 12.5 mg/kg</p> Signup and view all the answers

    What clinical feature is characteristic of Pityriasis Versicolor?

    <p>Asymptomatic macules with scaling</p> Signup and view all the answers

    Which factor is a significant predisposing condition for candidiasis?

    <p>Old age</p> Signup and view all the answers

    What is the appearance of Malassezia furfur observed under a KOH smear?

    <p>Spaghetti and meatballs</p> Signup and view all the answers

    Which antifungal is NOT mentioned as effective for Pityriasis Versicolor?

    <p>Fluconazole</p> Signup and view all the answers

    Which systemic treatment is recommended for Tinea Cruris?

    <p>Terbinafine 250 mg once daily</p> Signup and view all the answers

    What is the most common demographic group affected by Pityriasis Versicolor?

    <p>Adolescent and young adult males</p> Signup and view all the answers

    Study Notes

    Fungal Skin Infections

    • Fungal skin infections, also known as superficial mycoses, affect various superficial structures including hair, nails, and the stratum corneum of the skin.
    • Fungi causing these infections are called dermatophytes.
    • Dermatophytes are classified into three categories based on their ecology:
      • Geophilic: Live in soil.
      • Zoophilic: Primarily parasitize animal bodies, but can be transmitted to humans.
      • Anthropophilic: Usually infect humans and spread between individuals.
    • Dermatophytosis (ringworm): Infection of keratinized structures (hair, nails, skin).
    • Specific types of dermatophytosis include:
      • Tinea capitis (scalp)
      • Tinea barbae (beard and mustache)
      • Tinea faciei (face)
      • Tinea corporis (body)
      • Tinea cruris (groin)
      • Tinea manuum (hands)
      • Tinea pedis (feet)
      • Tinea unguium (nails)
      • Tinea incognito (obscured by steroid treatment).
    • Tinea corporis lesions are annular, with raised edges (active border) and a clearing center, involving glabrous skin (e.g., T. rubrum, T. mentagrophytes, M. canis).
    • Clinical variants of tinea corporis include:
      • Circinate typical lesion.
      • Tinea gladiatorum (common in contact sports).
      • Tinea imbricata (characterized by concentric rings),
      • Tinea incognito (altered by steroid use).
      • Majocchi granuloma (nodular perifolliculitis).
    • Tinea cruris (jock itch): Groin infection, typically on the upper medial thigh spreading to buttock and pubic regions, rarely involving the scrotum. Common in warm, moist environments.

    General Knowledge of Fungi

    • Yeast are unicellular fungi, often found at 37°C (body temperature).
    • Mold fungi are multicellular, characterized by hyphae (filaments), often observed at 25°C.
    • Dimorphic fungi: Can exist as mold or yeast depending on temperature conditions (e.g., molds at 25°C and yeast forming at 37°C).

    Skin Anatomy

    • Epidermis: Outermost skin layer.
    • Dermis: Inner skin layer containing blood vessels, hair follicles, sebaceous glands, and sweat glands.
    • Subcutaneous layer/Hypodermis: Layer beneath the dermis, primarily composed of fat.
    • Hair follicles, Sebaceous glands, Sweat glands: Structures within the dermis.
    • Pore: Opening of structures like hair follicles and sweat glands.
    • Hair and Nails: Keratinized structures.

    Candidiasis

    • Characterized by overgrowth of Candida yeast, Candida is a commensal organism in the human body which becomes pathogenic in presence of predisposing factors.
    • Predisposing factors includes:
      • Immunosuppression.
      • Pregnancy.
      • Diabetes.
      • Use of antibiotics.
    • Sites of candidal infection:
      • Skin (intertrigo, diaper candidiasis).
      • Mucous membranes (oral thrush, vulvovaginitis).
      • Nails (paronychia, onychomycosis).
    • Different clinical manifestations include thrush, vulvovaginitis, intertrigo, paronychia.

    Pityriasis versicolor

    • Chronic superficial fungal skin disease caused by lipophilic yeasts Malassezia furfur and M. globosa.
    • Lesions appear as asymptomatic, small, hypopigmented or hyperpigmented macules, typically on the back, underarms, upper arms, and chest.
    • Most common in adolescent and young adult males.
    • Associated with hot and humid climates and sweating.

    Investigations for Fungal Infections

    • Microscopic examination of skin scrapings in potassium hydroxide (KOH) mount to identify fungi and hyphae.
    • Skin culture to identify the species of fungus.
    • Wood's lamp examination for characteristic fluorescence (e.g., in tinea capitis).
    • KOH exams will reveal characteristic fungus structures (e.g., budding yeast, pseudohyphae).

    Treatment of Fungal Infections

    • Local: Topical antifungal creams, lotions, or shampoos. Examples are imidazoles, clotrimazole, ketoconazole, terbinafine, amorolfine and tioconazole.
    • Systemic: Oral antifungals (e.g., terbinafine, itraconazole, griseofulvin) are recommended for extensive or deep infections.
    • Anti-fungal therapy is classified according to the site of action:
      • At the nuclear level (flucytosine)
      • At the cytoplasmic membrane level (polyenes, azoles, allylamines).
      • At the cell wall level (echinocandins)
      • At the mitotic spindle level (griseofulvin).

    Differential Diagnoses

    • Conditions that can mimic fungal infections need to be considered in differential diagnosis. Examples include seborrheic dermatitis, psoriasis, eczema, and other skin diseases.

    Complications from Fungal Infections

    • Scarring alopecia can result from severe ringworm infections.
    • Ringworm infection can be rampant in schools and can spread rapidly between individuals.
    • Steroid use can mask the appearance of a fungal infection.

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    Fungal Skin Infection PDF

    Description

    Explore the world of fungal skin infections, specifically focusing on dermatophytes and their classification. This quiz covers various types of infections such as tinea capitis and tinea pedis, providing insights into their effects on skin, hair, and nails. Test your knowledge about these common yet important conditions.

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