2Fungal skin Infections The most common cutaneous infectionReferred to as ring worm infectionsUsually superficial and can involve hair, nail, skin.Tinea capitis,tinea corporis, tinea pedisThree genera of fungi: Trichophyton, Microsporum and EpidermophytonPredisposing factors:Trauma to the skin: blistersDiabetes or immunocompromised patientsSkin occlusion, high humid conditionsTinea pedis: Athlete’s foot: the most prevalent fungal infectionMore 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 overweightTinea capitis: scalp is involved, common among children
3Environmental factors play an important role EpidemiologyTraumaEnvironmental factors play an important roleChronic health problems and medications that weaken immune responseTinea pedis is the most common infectionEtiology: three genera of pathogenic fungi: trichophyton, microsporum and epidermophytonTransmission: contact with infected people, fomites. Environmental factorsPathophysiology:InoculationIncubation period: dermatophyte grows in SC, minimal signs of infectionInfection is established: fungal growth rate vs epidermal growth rateSerum inhibitory factor inhibits further growthDermatophyte starts secreting enzymes and keratinases and reach the viable epidermisCell mediated immunity starts: inflammation and pruritisSigns and symptoms of infectionMild itching and scaling to severe exudative inflammatory process. Fissuring, crusting and discoloration of the skin
5Tinea PedisFour accepted variants are presentChronic intertriginous type: most common, fissuring , scaling, maceration in the interdigital space. Malodor, pruritis.Chronic papulosquamous: both feet, mild inflammation and diffuse scaling of the solesVesicular type: small vesicles. Skin scaling may be seenAcute ulcerative type: macerated weeping ulceration on the sole. Hyperkeratosis and pungent odorInfection may trigger a bacterial overgrowthBE CAREFUL WHEN:Toe nail is involved, vesiculareruptions with ooszing,eczematous eruptions withblisters, diabetic patients
6Tinea unguium: nails are infected The gradually loose their shiny luster and become opaqueIf untreated, the nails become thick, yellowish and friableThe nail may separate from the nail bed and may be lost
7Tinea corporis: has diverse clinical presentation. Lesions start as small circular erythematous scaly areasSpread peripherally and the borders may contain vesicles.Pruritis
9Tinea 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 scalp2. Inflammatory, pustules to kerions/ Kerion: weeping lesions, exudates, form thick crusts on the scalp. Pruritis, fever, pain, lymph nodes3. Black dots - the hairs are broken off at the scalp surface, which is scalySmooth areas of hair loss4.Favus – patchy areas of hair loss, yellow crusts and matted hairUntreated kerion and favus may result in permanent scarring (bald areas).
11Treatment of fungal skin infections Goals: provide symptomatic relief, eradicate the infection, prevent future infectionsPharmacologic agents: antifungals, antiinflammatory agents, astringent salts for tinea pedis before therapyPatient compliance: 2-4 weeks for the infection to be eradicatedNon pharmacologic measures: keep the skin dry and clean, avoid sharing personal articlesAntifungals:Clioquinol 3%: pedis, corporiswith hydrocortisoneClotrimazole, miconazole nitrate: pedis and corporisTerbinafine hydrochloride: 1%TolnaftateSalts of aluminum: no direct antifungal effect, reduce iflammation, astringents, decrease edema, inflammation and irritation. Aluminum acetate and chloride