Ch. 41 Fungal Skin Infections

Question 1

Fungal Skin Infections

Answer 1

• AKA dermatomycoses, common cutaneous disorders
• AK ringworm, clear centers with red/scaly borders
• Tinea - dermatomycophyte infections
• Usually superficial and can involve hair, nails, and skin
• Usually caused by 3 genera of fungi but can also include candida and yeast
• Trauma to skin significantly more important than exposure to the pathogen
• Worsening factors: diabetes, poor nutrition, immunosuppression, poor circulation, hygiene, occlusion of skin, warm/humid cliates

Question 2

Tinea Pedis

Answer 2

• Most common
• Effects more men, common in white people
• More common as adults
• Increased risk when used public pools and baths or participating in high impact sports
• Wearing socks/shoes worsens it by retaining heat and moisture which helps fungus grow

Question 3

Tinea Unguium

Answer 3

• 2nd most common
• Nail fungus
• 1/2 of nail disorders
• Not approved for self treatment

Question 4

Tinea Corporis

Answer 4

• Body

- More common in kids who go to daycare or in contact sports

Question 5

Tinea Cruris

Answer 5

• Jock itch
• More common in warm weather
• Occurs more in men from prolonged exposure to wet clothing or skin

Question 6

Tinea Capitis

Answer 6

• Scalp
• Happens most in children from an unknown incidence
• Black, female children are most effected
• Can be spread by direct contact, fomites, or infected dogs/cats
• No self treatment

Question 7

Fungal Infection Pathophysiology

Answer 7

• 3 genera: Trichophyton (T), Microsporum (M), and Epidermophyton (E)
• Pedis and cruris: E & T
• Capitis: T & M
• Unguium - T
• All cause corporis
• Dermatophyte classifications: anthropophilic (human), zoophilic (animals), geophilic (soil)
• Human to human is the most common transmission
• Environmental factors: warmth and humidity
• Glucocorticoids decrease immune function and increase tinea
• Once in skin, a dermatophyte goes through incubation, enlargement, refractory period, and stage of involution
• Lesion size/duration is determined by organism growth and epidermal turnover rate, growth must outweigh turnover rate else it will be shed
• SIF inhibits growth beyond the stratum corneum
• Dermatophyte also produces keratinases and enzymes that causes type IV allergic reaction
• Causes inflammation and pruritic, after this immunologic response symptoms can decrease and infection may clear spontaneously in involution
• Chronic infection: decreased inflammation and decreased hypersensitivity

Question 8

Fungal Presentation

Answer 8

• Range: mild itching to scaling to severe, exudative inflammation (fissuring, crusting, discoloration)
• First infections and secondary zoophilic fungi tend to have increased inflammation

Question 9

Tinea Pedis Presentation

Answer 9

• 4 variants, 2+ of which may overlap
• Most common: chronic intertriginous type; fissuring, scaling, malodor, pruritic, stinging
• Occurs between outer toes, can spread to sole and instep
• Need to treat sweating too since it can worse the infestation
• Normal aerobic diphtheroids may become involved from increased moisture and temperature which can worsen the condition

Question 10

Chronic Papulosquamous

Answer 10

• 2nd most common variant of tinea pedis
• Both feet, mild inflammation, moccasin like scaling on soles
• May also have nail fungi on 1+ toenails
• Must cure toenails first (will fuel infection) with treatment or remove it surgically

Question 11

Trichophyton Mentagropytes var. Interdigitale

Answer 11

• Vesicular type of tinea pedis
• Vesicles in instep/midplantar
• Skin scaling seen on instep and on toe webs
• Worsens in warmer weather

Question 12

Acute Ulcerative Type

Answer 12

• 4th variant of tinea pedis
• Macerated, denuded, weeping ulcers on sole
• White hyperkeratosis and malodor usually present
• Complicated by gram negative overgrowth, proteus, or pseudomonas - “Dermatophytosis complex”
• Extremely painful, erosive, purulent interspace
• Can impede walking

Question 13

Tinea Unguium Presentation

Answer 13

• Nails become opaque, thick, rough, yellow, friable
• No OTC treatment
• Many separate from bed if secondary to subungual hyperkeratosis
• Nail may be lost all together and secondary infection can occur under the nail

Question 14

Tinea Corporis Presentation

Answer 14

• Diverse presentation, but mostly small, circular, erythematous, scaly lesions on smooth/bare skin
• Spread peripherally and can contain vesicles or pustules
• Pruritis is also common complaint
• Areas they can occur can give a clue to their classification
• Zoophilic: exposed skin neck, face, and arms
• Anthrophilic: usually occluded or trauma areas

Question 15

Tinea Cruris Presentation

Answer 15

• More common on males on the inner thigh and pubic area
• Well-demarcated lesions with slightly elevated red boarders and clearer center
• Finer scaling is usually present and hyperpigmentation is more common in chronic cases
• Usually bilateral with pruritic
• Usually spares penis and scrotum, if on these areas it may be candidiasis instead
• Pain can occur during sweating or secondary infections/macerations

Question 16

Tinea Capitis Presentation

Answer 16

• 4 patterns depending on dermatophyte
• Noninflammatory: lesions, small papules that spread to all hair shafts in its path, some scaling, minorly inflammatory, gray hair in lesions that breaks off
• Inflammatory: inflammation from pustules to kerion formation (weeping lesions that exudate thick scales). Associated with fever, pain, increased pruritic, enlarged lymph nodes
• Black dot: anthrospores causes hair to break off and leave black dots at the surface. Causes hair loss, inflammation, and scaling. Can be mild to extensive and hard to diagnose
• Favus Variant: patchy hair loss and scutula (yellow crusts/scales), can morph to involve large portions of the scalp. Left untreated secondary infections, scalp atrophy, scarring, and permanent hair loss can occur

Question 17

Fungal Treatment Goals

Answer 17

1. Symptomatic Relief
2. Eradicate existing infection
3. Prevent future infections

Question 18

Fungal General Treatment

Answer 18

• Can self treat pedis, corporis, and cruris only
• Can use Fungal Nail Revitalizer to improve nail appearance during Rx treatment, doesn’t treat tinea
• See PCP if doubting that tinea is the cause
• Choose antifungal and formulation based on tinea type
• Patient must be able to adhere to therapies for needed amount of time for them to be effective, some of which are 2-4 weeks
• Also need to adhere to preventative nonpharmacologic measures to stop future infection
• These include keeping skin clean and dry, avoiding sharing personal items, avoiding infected fomites, individuals, or pets

Question 19

Tinea Nonpharmacologic

Answer 19

• Preventative measures
• These include keeping skin clean and dry, avoiding sharing personal items, avoiding infected fomites, individuals, or pets

Question 20

Tinea Pharmacologic

Answer 20

• Must have one well-designed clinical trial showing its effectiveness against tinea for FDA approval
• Treat athlete’s foot, jock itch, and ringworm
• Minimal treatment period: 1-4 weeks

Question 21

Clotrimazole & Miconazole

Answer 21

• Imidazole derivatives that have fungistatic and fungicidal activity that is concentration dependent
• Inhibit synthesis of ergosterol and other sterols which causes cell wall breakdown
• Also inhibits oxidative and perioxidative enzyme activity which increase toxic metabolite concentrations and leads to cell necrosis
• In C. Albicans, causes inhibition of blastophere transformation to its invasive form that causes infection
• Clot 1% and Mic 2% = safe, OTC for pedis, cruris, and corporis
• Apply in morning and evening for 4 weeks for pedis and corporis, 2 week for cruris
• SE (rare): irritation, burning, stinging
• No drug-drug interactions

Question 22

Terbinafine HCl

Answer 22

• 1% reclassified to OTC in 1999
• Inhibits squalene epoxide for sterol synthesis
• Apply sparingly to AA twice a day
• Cures pedis in 1 week trials, but took 4 weeks for compete symptom resolution
• 2x/day x 1 week: interweb pedis, cruris, and corporis
• 2x/day x 2 weeks: soles/sides pedis
• PCP may give different instructions of use, follow their directions if they differ
• Rare SE: irritation, burning, itching, dryness
• No drug-drug interactions

Question 23

Butenafine HCl

Answer 23

• 1% reclassified to OTC in 2001
• Same MOA as terbinafine
• For interweb pedis, cruris, and corporis
• Also treats itching, burning, cracking, and scaling of these conditions
• Unknown efficacy for bottom/sides of feet
• Pedis: 1x/day x 4 weeks or 2x/day x 1 week
• Cruris/Corporis: 1x/day x 2 weeks
• Increased efficacy with increased treatment time
• PCP may give different instructions of use, follow their directions if they differ
• Low incidence of SE and no drug-drug interactions

Question 24

Tolnaftate

Answer 24

• Standard for other antifungals for years
• MOA not reported, believe to distort the hyphae and stunt mycelial growth
• Only one approved for tinea infections
• Best on dry, scaly lesions
• Relapse sometimes occur upon D/C
• Solidifies in cold but liquifies without potency loss in warmth
• Cream and solution are best for superficial tinea
• Aerosol and powder can absorb excess moisture
• Apply sparingly 2x/day for 2-4 weeks, may be more like 4-6 weeks on feet
• Can be applied to intact or broken skin
• Allergic reactions are rare and no drug-drug interactions

Question 25

Clioquinol/Haloprogin/Undecylenic Acid

Answer 25

• Not commercially available

- Approved by FDA for OTC use

Question 26

Salts of Aluminum

Answer 26

• Relieve inflammation (FDA approved), not tinea
• Can be used to treat wet, soggy pedis types of infections
• Useful in combination with order antifungals
• Shifts wet soggy pedis to dry athlete’s foot
• Acts as astringent: decreases edema, exudation, and inflammation by decreasing cell permeability and hardening intercellular cement
• > 20% = antibacterial that may help prevents secondary infections
• Diluted 10-40 parts water, can immerse foot in solution or apply as wet dressings
• Use 2x daily until symptoms stop (odor, wetness, whiteness)
• Once controlled, can use once daily to maintain
• Little is absorbed so causes little toxicity
• CI: deep fissures or severely eroded skin; if these occur, lower the concentration of dilutions
• Don’t apply near eyes, prolonged use can cause tissue necrosis, use <1 week for inflamed pedis and D/C if condition worsens

Question 27

Tinea Pharmacotherapeutic Comparisons

Answer 27

• Butenafine and terbinafine are good for 1 week cures of athlete’s foot, but better results with longer use
• Clot. and Mic. can also be recommended depending on patient’s ability to adhere to treatment

Question 28

Tinea Product Selection Guidelines

Answer 28

• Creams and solutions are the most effective forms
• Sprays and powders are better as adjuncts or prophylaxis treatment
• Recommend therapy based on needs, easy preparations for elderly, talcum powder on fat and in shoes for obese
• Consult caregiver when appropriate
• Get medical history to distinguish from other conditions (Diabetes for example)
• Mention that different brans or forms of a brand can have different active ingredients and how that can change how they use or what to expect for the med

Question 29

Tinea Complementary Therapies

Answer 29

• Bitter orange, tea tree oil, and garlic has shown some success, need further investigation
• Bitter orange: least evidence of safety/efficacy, but improved all tinea forms when used TID for 1-4 weeks
• SE: mild, local irritation
• Tea tree oil: mixed results; treats scaling, inflammation, itching, and burning equally to tolnaftate
• Used in 10% preparations, not mycologic cure
• At 25% and 50% is a symptomatic and mycologic cure but still inferior to butenafine and clotrimazole
• Garlic gel with 0.6% ajoene was equally effective as 1% terbinafine, and at lower concentrations still shown to be a symptomatic and mycologic cure with 2 week use
• 1% garlic may be a better option than terbinafine

Question 30

Tinea Assessment

Answer 30

-Need to physically eamine to differentiate from bacterial infection and noninfectious dermatitis
-Question patient about symptoms, characteristics, etc. (SCHOLAR MAC)
-Inspect private, sanitary area, especially if they have diabetes
Most common complaint: pruritic
-Symptom complaint can vary greatly depending on tinea type and severity
-Ask about footwear and changes
-Hyperhidrosis: common, tender vesicles covering soles of feet or toes, painful
-Excessive sweat, foul odor, and white eroded skin are all common in tinea pedis

Question 31

Tinea Counseling

Answer 31

• Technique/duration of therapy
• Apply medication regularly
• Methods to control or eradicate infection and prevent future infections
• These include laundry techniques, footwear, avoiding habits/behaviors of infections
• Which conditions or symptoms require PCP

Question 32

Tinea Evaluation

Answer 32

• Should see some relief in 1 week
• If improved in 1 week, continue treatment for another 1-3 weeks
• If not improvement or worsening, see doctor
• Recurrent infections can be indicative of more serious conditions that require a medical referral