Fungal Infections and Treatments Quiz

Fungal Skin Infections

• Fungal skin infections are categorized as superficial, subcutaneous/deep, and systemic.
• Superficial mycoses affect the outer layer of skin, hair, and nails.
• Subcutaneous mycoses impact the dermis or subcutaneous tissue due to fungal implantation post injury.
• Systemic mycoses (true pathogens) spread via blood or from adjacent structures. They are opportunistic infections in immunocompromised hosts.

Basic Anatomy of the Skin

• The skin's epidermis is the outermost layer.
• The dermis is the underlying layer of connective tissue.
• The subcutaneous tissue is the layer below the dermis.
• The skin contains structures like hair, sebaceous glands, sensory nerve endings, sweat glands, capillaries, and muscle tissue, along with collagen, fat, and fibroblasts.

Epidermis

• The epidermis is composed of layers of cells with specialized roles.
• Keratinocytes are flattened cells filled with keratin.
• Langerhans cells aid in the immune system.
• Merkel cells play a part in sensory perception.
• Stem cells are actively dividing to regenerate the skin.
• Glycolipids are present in spaces between cells.
• Lamellar granules and keratohyaline granules are involved in cell function within the layers.
• Intermediate filaments made of pre-keratin are present.

Dermis

• The dermis is a fibrous connective tissue layer supporting the skin.
• The dermis contains blood vessels, lymph vessels, hair follicles, sweat glands, sebaceous glands, collagen bundles, fibroblasts, nerves, and arrector pili muscles.
• It supports the skin through supportive connective tissue elements.

Fungal Infections of the Skin

• Superficial mycoses involve the stratum corneum, hair, and nails.
• Subcutaneous mycoses infiltrate dermis and subcutaneous tissue due to implantation via skin trauma.
• Systemic mycoses (true pathogens) disseminate via blood or extension from adjacent structures. Opportunistic infections tend to occur in immunocompromised individuals.

Fungi Causing Superficial Mycoses

• Dermatophytes: Trichophyton, Microsporum, Epidermophyton.
• Yeasts/Candida: Candida skin infection.
• Malassezia: Pityriasis (tinea) versicolor, Malassezia (pityrosporum) folliculitis.
• Other Molds: Scopulariopsis, Scytalidium, Fusarium, Aspergillus

Dermatophytes (Dermatophytoses)

• Dermatophytes are fungi capable of infecting keratin. They infect the stratum corneum, hair, and nails.
• Types of dermatophytes include Trichophyton (pencil-shaped), Microsporum (spindle-shaped), and Epidermophyton (club-shaped).
• There are different types categorized by transmission: Anthrophilic (human-to-human), Zoophilic (animal-to-human), and Geophilic (soil-to-human/animal).
• Diseases are named as tinea followed by the body part, for example, tinea corporis (body), tinea pedis (feet), tinea capitis (scalp), tinea cruris (groin), tinea faciei (face), tinea unguium (nails/fingernails), tinea manuum (hands), tinea barbae (beard, mustache), and tinea incognito (atypical infection altered by steroid use).
• Subtypes include epidermal dermatophytosis (epidermomycoses), dermatophytosis of hair and hair follicles (trichomycoses), and dermatophytosis of nail apparatus (onychomycoses).

Sources of Fungi

• Endogenous: Fungi are part of the body's resident flora (e.g., Candida, Malassezia). Infection arises when conditions allow fungi to transition from saprophyte to pathogen.
• Exogenous: True pathogenic fungi originate from external sources like animals (zoophilic), soil (geophilic), or other humans (anthrophilic).

Lab Investigations

• Direct Microscopy: Skin samples are examined under a microscope after applying a KOH solution.
• Wood's lamp examination reveals fluorescence of some fungi
• Culture: Specimens are grown on Sabouraud's glucose medium.
• Skin Biopsy (Dermatopathology): PAS stain identifies fungal elements. Skin biopsies are performed to confirm diagnosis of fungal infection.

Treatment

• Treat fungal infections with specific antifungal agents (topicals and systemics).
• Topical agents include clotrimazole, miconazole, ketoconazole, econazole, imidazole, terbinafine, naftifine, and tolnaftate (antifungal creams, lotions).
• Systemic agents include griseofulvin, itraconazole, terbinafine, and fluconazole (antifungal tablets/capsules).
• Combination therapy combines topical and systemic antifungal medications, often necessary for deeper or widespread infections.
• Sometimes, removal of the affected nail is required for treatment.

Pityriasis Versicolor

• A chronic, asymptomatic superficial fungal infection.
• Typically presents as well-demarcated scaling patches with variable pigmentation, typically on the trunk.
• Caused by the fungus Malassezia furfur.
• M. furfur (synonym Pityrosporum ovale, P. orbiculare) is characterized as round yeasts and elongated pseudohyphae, sometimes styled "spaghetti and meatballs".

Superficial Candidiasis

• Predominantly caused by Candida albicans
• Predisposing factors include conditions like diabetes, cancer, or immunosuppressant therapies.
• Clinical features may include oral candidiasis, vulvovaginal candidiasis, candida intertrigo, and chronic mucocutaneous candidiasis.
• Diagnosable through microscopy. Budding yeasts with hyphae or pseudohyphae are evident. Culture is rapid-growing and smooth, typically cream-coloured.
• Topical antifungals (e.g., clotrimazole, miconazole, tioconazole) are used
• Extensive cutaneous candidiasis* is treated with systemic antifungals (e.g., itraconazole or fluconazole) or nystatin, also employed to treat oral candidiasis.

Subcutaneous / Deep Mycoses

• Includes chromoblastomycosis, mycetoma, sporotrichosis.

Systemic Mycoses

• Includes blastomycosis, cryptococcosis, histoplasmosis.

Test your knowledge on fungal infections, specifically focusing on Candida infections and their clinical features. This quiz covers diagnosis, treatment options, and general characteristics of related fungal conditions. Challenge yourself and see how well you understand these important medical topics.