Download L06 Para Fungal-infections 2015

FUNGAL SKIN INFECTIONS
Fungal skin Infections
• The most common cutaneous infection
• Referred to as ring worm infections
• Usually superficial and can involve hair, nail, skin.
• Tinea capitis,tinea corporis, tinea pedis
•Three genera of fungi: Trichophyton, Microsporum and Epidermophyton
Predisposing factors:
Trauma to the skin: blisters
Diabetes or immunocompromised patients
Skin occlusion, high humid conditions
Tinea pedis: Athlete’s foot: the most prevalent fungal infection
More common in adults than in children, more in men than in women,
Tinea corporis: common among children, hot and humid conditions,
individuals under stress and overweight
Tinea capitis: scalp is involved, common among children
Epidemiology
•Trauma
• Environmental factors play an important role
• Chronic health problems and medications that weaken immune response
•Tinea pedis is the most common infection
Etiology: three genera of pathogenic fungi: trichophyton, microsporum and
epidermophyton
Transmission: contact with infected people, fomites. Environmental factors
Pathophysiology:
• Inoculation
• Incubation period: dermatophyte grows in SC, minimal signs of infection
• Infection is established: fungal growth rate vs epidermal growth rate
• Serum inhibitory factor inhibits further growth
• Dermatophyte starts secreting enzymes and keratinases and reach the
viable epidermis
• Cell mediated immunity starts: inflammation and pruritis
Signs and symptoms of infection
Mild itching and scaling to severe exudative inflammatory process. Fissuring,
crusting and discoloration of the skin
Tinea Pedis
Four accepted variants are present
1. Chronic intertriginous type: most
common, fissuring , scaling,
maceration in the interdigital
space. Malodor, pruritis.
2. Chronic papulosquamous: both
feet, mild inflammation and diffuse
scaling of the soles
3. Vesicular type: small vesicles. Skin
scaling may be seen
4. Acute ulcerative type: macerated
weeping ulceration on the sole.
Hyperkeratosis and pungent odor
• Infection may trigger a bacterial
overgrowth
• BE CAREFUL WHEN:
Toe nail is involved, vesicular
eruptions with ooszing,
eczematous eruptions with
blisters, diabetic patients
•
•
•
•
Tinea unguium: nails are infected
The gradually loose their shiny luster and become opaque
If untreated, the nails become thick, yellowish and friable
The nail may separate from the nail bed and may be lost
• Tinea corporis: has diverse
clinical presentation.
• Lesions start as small circular
erythematous scaly areas
• Spread peripherally and the
borders may contain vesicles.
• Pruritis
Tinea capitis: most prevalent between 3 - 7 years of age.
It is slightly more common in boys than girls.
More common in crowded living conditions.
The fungus can contaminate hairbrushes, clothing, towels and the backs of
seats. The spores are long lived and can infect another individual months later.
Tinea capitis may present in several ways.
1. Dry scaling – non inflammatory. Small papules surrounding the shafts, like
dandruff but usually non inflammatory, spreads centrifugally, hair lesions are dull
gray in color, hair breaks off the scalp
2. Inflammatory, pustules to kerions/ Kerion: weeping lesions, exudates, form
thick crusts on the scalp. Pruritis, fever, pain, lymph nodes
3. Black dots - the hairs are broken off at the scalp surface, which is scaly
Smooth areas of hair loss
4.Favus – patchy areas of hair loss, yellow crusts and matted hair
Untreated kerion and favus may result in permanent scarring (bald areas).
Treatment of fungal skin infections
Goals: provide symptomatic relief, eradicate the infection, prevent future
infections
•Pharmacologic agents: antifungals, antiinflammatory agents, astringent
salts for tinea pedis before therapy
•Patient compliance: 2-4 weeks for the infection to be eradicated
•Non pharmacologic measures: keep the skin dry and clean, avoid sharing
personal articles
Antifungals:
Clioquinol 3%: pedis, corporis
with hydrocortisone
Clotrimazole, miconazole nitrate: pedis and corporis
Terbinafine hydrochloride: 1%
Tolnaftate
Salts of aluminum: no direct antifungal effect, reduce iflammation,
astringents, decrease edema, inflammation and irritation. Aluminum acetate
and chloride