Fungal Infections Flashcards
Risk Factors for Fungal Skin Infections
- Trauma to the skin (blisters from ill-fitting footwear)
- Diabetes mellitus
- Obesity
- Immunosuppression: drugs (glucocorticoids, chemotherapy), diseases (HIV)
- Impaired circulation
- Poor nutrition & hygiene
- Occlusion of the skin
- Climate: warm, humid climates
- Some infections: spread by direct contact with infected fomites (combs, clothing, linens)
Clinical Presentation: Sign/Sx
- Pruritus (most common), burning / stinging pain
- Inflammation, redness, macerated skin
- Foul odor: associated with hyperhidrosis and gram-negative bacterial infection
- Weeping, oozing pus
- Scaling
- Fissures
- Small vesicular lesions
- Nail changes (brittle or discolored hypertrophied nail)
Exclusions for Self-Treatment
- Causative factor unclear
- Initial treatment unsuccessful/worsening
- Involvement of face, mucous membrane, genitalia, nails or scalp
- Signs of possible secondary infection
- Excessive/continuous exudation
- Extensive, debilitating, extreme inflammation
- Diabetes, systemic infection, immune deficiency
- Fever, malaise
Pathophysiology: Tinea
= fungal infection of skin caused by dermatophytes
Pathophysiology: Causative Organisms
- Trichophyton
- Microsporum
- Epidermophyton
Pathophysiology: Stages of Infection
- Inoculation (dermatophyte infects skin)
- Incubation (fungal growth)
- Refractory (epidural turnover, symptomatic phase)
- Involution (immune response, resolution of sx)
Pathophysiology: Transmission
Contact with infected people, animals, soil, fomites (contaminated objects)
Infection named based on body part
- Tinea pedis (feet) (most common)
- Tinea corporis (body)
- Tinea cruris (groin)
- Tinea unguium (nails)
- Tinea capitis (scalp)
Tinea Pedis (Athlete’s Foot)
- Most prevalent cutaneous infection in humans
- RF: communal areas, athletes
4 types:
- Chronic intertriginous: most common, interdigital (can spread to sole), fissuring, scaling, maceration, malodor, pruritis, stinging
- Chronic papulosquamous pattern: bilateral on both feet, mild inflammation, diffuse moccasin-like scaling on soles (+nails)
- Vesicular: small vesicles near instep on mid-anterior plantar surface, skin scaling, summer
- Acute ulcerative: macerated, denuded, weeping ulcerations on sole, odor, white hyperkeratosis, gram-negative bacteria
Tinea Corporis (Ringworm)
- Most common in pre-pubescent children, hot/humid areas, stress/obesity, contact sports
- On glaborous (smooth/bare) skin
- Small, circular erythematous, scaly area with vesicles in borders spread peripherally, borders with pustules or vesicles
- Pruritis
Tinea Cruris (Jock Itch)
- Common in warm weather or if skin moist/wet for long periods (occlusive clothing)
- More common in males
- Bilateral infection: inside/upper thigh, pubic area
- Lesions with very clear and slightly elevated margins, with erythema in central areas
- Significant pruritis/pain
- Generally spare penis/scrotum (can differentiate from Candida)
Tinea Unguium (Ringworm of Nails)
- EXCLUDED from self-treatment
- Older age, swimming, tinea pedis, immunodeficiency, diabetes, infected family members
- Nails become thick, yellow, rough, etc., may become separated from nail bed, sublingual hyperkeratosis
Tinea Capitis (Ringworm of the Scalp)
- EXCLUDED from self-treatment
- Direct contact with infected individuals / fomites
4 variants
- Non-inflammatory: small papules
- Inflammatory: pustules -> kerion
- Black dot: hair breaks off, leaves black dot
- Favus: patchy hair loss, scutula -> atrophy, scars
Goals of Self-Treatment
- Relieve symptoms
- Cure the infection
- Prevent future infections (use good hygiene)
- Prevent complications
a. Secondary infections
b. Permanent hair loss
c. Scarring
Non-Pharmacologic Therapies
- Good hygiene: cleanse daily with soap and water and pat dry
- Keep the area dry: allow shoes to dry before wearing, limit use of occlusive (wool/synthetics) or wet clothing
- Prevent spread: launder in hot water, do not share towels/personal articles, use a separate towel to dry affected area
- Prevent acquisition of infection: avoid close contact with infected individuals, protective footwear in shared areas
OTC Antifungal Dosage Forms
- Creams: penetrate stratum corneum well (good for dry/cracked skin), adheres well
- Solutions: ideal for moist/oozing areas, easily applied, but must allow to air dry
- Creams and solutions: most efficient and effective in delivering drug to epidermis*
- Ointments: oil-based, occlusive, greasy, not ideal for wet/macerated tissues
- Sprays: convenient, no touch (spray 6–10 inches away), caution with eyes
- Powder/Spray Powder: use for large areas, Tolnaftate powder contains cornstarch and talc to absorb moisture
- Sprays/powders: less effective (not rubbed in), however may improve adherence since they are easy to apply*
Terbinafine
Squalene-epoxidase inhibitor:
- Depletes egosterol, prevents fungal growth (fungistatic)
- Causes accumulation of intracellular squalene, kills fungus (fungicidal)
- For age >= 12 yo
- All 1% concentration
- Shortest acting treatment for TP
FOR TP BETWEEN TOES:
- Spray: BID x 2 weeks
- Solution: BID x 2 weeks
- Cream: BID x 1 week
- Gel: Once daily x 1 week
FOR TP BOTTOM/SIDE:
- Cream: BID x 2 weeks
FOR T cruris/corporis:
- ^ALL: Once daily x 1 week
Butenafine
Squalene-epoxidase inhibitor:
- Depletes egosterol, prevents fungal growth (fungistatic)
- Causes accumulation of intracellular squalene, kills fungus (fungicidal)
- For ages >= 12 yo
- 1% concentration cream
FOR TP BETWEEN TOES:
- Once daily x 4 weeks* or BID x 7 days
FOR T cruris/corporis:
- Once daily x 2 weeks
Azoles
• Prevent de-methylation of lanosterol, stop synthesis of cell wall (fungistatic)
• Clotrimazole AND Micronazole Nitrate Topicals - Both: Age >= 2 yo - BOTH FOR TP AND T corporis: • Solution/Cream/Oint: BID x 4 weeks - FOR T cruris: • Solution/Cream/Oint: BID x 2 weeks
Tolnaftate
Thiocarbamate antifungal
- Exact MOA not reported: distort hyphae, stunt mycelial growth of fungi species
FOR TP/TC/TC:
- ALL versions: BID x 2-4 weeks
AE: stinging
Note: Tolnaftate powder may not be effective as monotherapy
Undecylenic acid and Undecylenate salts
- Unsaturated fatty acids that impact fungal growth (fungistatic), similar efficacy to tolnaftate
• Undecylenic Acid: Age >= 2 yo FOR TP AND T corporis - 25% Liquid/Oint: BID x 4 weeks FOR T cruris: - 25% Oint: BID x 2 weeks
Salts of Aluminum (MOA/AE/W)
- Al acetate (Burow’s solution)
- Al sulf tetradecahydrate + Ca acetate Monohydrate (Domeboro®)
^BOTH for acute inflammatory, wet/soggy TP
- MOA: astringent and antibacterial
- Uses: combo therapy for TP, relief of inflammatory conditions of skin
• AE: skin dryness, burning, stinging, irritation, tissue necrosis
• Warnings:
- External use only, avoid eye contact
- Accidental child poisoning
- Prolong use can cause tissue necrosis (don’t use more than 1 week)
- Discontinue if lesions appear/worsen
Patient Education
- Clean and pat dry the affected area (do not share towels)
- Apply antifungal sparingly twice daily (AM and PM)
- Massage medication into the affected area
- Avoid touching the eyes
- Wash hands thoroughly with soap and water
- Expect improvement within 1 week, if not see provider
- Continue therapy for entire directed course (up to 6 weeks)
