皮肤性病学课件：Mycoses

1、 Mycoses Objective: 1) To master the conception of superficial and deep mycosis 2) To master the clinical features and treatmentsof tinea capitis 3) To master the clinical manifestations of four types tinea of hands and feet 4) To master the topical treatment of tinea pedis 5) To understand the prev

2、ention of tinea capitis and tinea pedis T.shoenleinii M.canis T.tonsurans T. mentagrophytes E.floccosumT.rubrum Introduction of mycoses What are mycoses? Mycoses are a group of diseases caused by fungi. They may involve humans, animals and plants. In humans, the skin constitutes the main site of rec

3、ognizable fungal infections, and these infections can be divided into superficial and deep mycoses. What are superficial mycoses? Superficial mycoses are superficial infections of keratinized tissue caused by organisms of three genera of fungi known as the dermatophytes. The infections are restricte

4、d to the skin and limited to a depth of 1 or 2 mm. The skin appendages, namely, the hair and nails, are also involved in these infections. Including: (1) tinea capitis (ringworm of the scalp and kerion) (2) tinea barbae(ringworm of the beard) (3) tinea faciei (4) tinea corporis (5) tinea pedis and t

5、inea manus (6) tinea cruris (8) onychomycosis(fungus infection of the nail) What are deep mycoses? Deep mycoses represent systemic or deep fungal infections and may have prominent cutaneous and systemic manifestations. They are mostly caused by yeast and mould. Mycology The dermatophytes represent m

6、ore the 40 closely related species classified in three genera:Microsporum, Trichophyton, and Epidermophyton.They digest and live on keratin. Mycologic procedures Microscopic examination 1) Hair: when the lesions involve the scalp and beard, examination with a Woods lamp will occasionally reveal hair

7、s infected with microsporum species. Suspected hairs are placed on microscope slides with clearing solution, to be examined by low-power microscopy . The fungus invades the hair shaft two ways: Ectothrix type: The hair is surrounded with a sheath of tiny spores. M species, as well as T. mentagrophyt

8、es and T. verrucosum, are ectothrix fungi. Endothrix type: The arthrospores are formed inside the hair shaft. This type is seen with T. tonsurans, T. violaceum, and T. schoenleinii infection. T. mentagrophytes E.floccosum M.canis T.tonsurans T.rubrum T.violaceum T.shoenleinii 2) Skin and nail: skin

9、samples are taken from the advancing margins of the lesion by scraping with the dulled edge of a scalpel. Nail specimens should include clipping of the entire thickness of the nail. The specimens are placed on a slide and covered with a drop of 10-20 percent solution of potassium hydroxide. Then a c

10、overslip is applied. The clearing solution (10-20% KOH) is used. The clearing process can be hastened by gently heating the slide. In a positive preparation, fungi will appear as septate and branching hyphal elements. 2. Culture procedures The clinical specimens are cultured on media suitable for gr

11、owth of these fungi. Sabouraudd glucose agar is the most commonly used medium in medical mycology. Cultures should be maintained at room temperature (26) for up to 4 weeks before they are discarded as showing no growth. Antifungal therapy Three considerations: (1) the spectrum of activity of the ant

12、ifungal agent; (2) pharmacokinetic profile of the agent; (3) the clinical type of infection. Additional considerations should be safety, compliance, and cost. Griseofulvin is still a viable therapeutic option in many cases; the newer antifungals are being shown to be more efficacious. The imidazoles

13、 comprise clotrimazole, miconazole, econazole, sulconazole, oxiconazole, ketoconazole and are used mostly for topical therapy. They work by inhibition of the cytochrome p450 14-demethylase, an essential enzyme in ergosterol synthesis. Nystatin is a polyene that works by irreversibly binding to ergos

14、terol, an essential component of fungal cell membranes. Allylamines: naftifin, terbinafine, butenafine. They work by inhibting squalene epoxydation. Triazoles: itraconazole, fluconazole. They affect the cytochrome p450 system. The triazoles have the broadest spectrum of activity, including dermatoph

15、ytes, Candida species, and Malassezia funfur. Food increases its absorption.Floconazoles absorption is not affected by food. Terbinafine is less active against Candia species; however, clinically is usually effective. It has been shown ineffective in the oral treatment of tinea vesicolor but is effe

16、ctive topically. Ketoconazole has a wide spectrum against dermatophytes, yeasts, and some systemic mycoses. It has the potential for serious drug interaction and a higher incidence of hepatotoxicity during long- term daily therapy. Prevention (prophylaxis) (1) To prevent transmission of infection. I

17、ncluding screening and treatment of family members, sterilization of the environment, proper treatment of infected animals. (2) Education: good personal hygiene and public hygiene Tinea capitis Tinea capitis is a dermatophytosis of the scalp and associated hair that is caused by a variety of species

18、 of the genera Microsporum and Trichophyton. It occurs chiefly in school children and less commonly in infants and adults. It is divided into four types: tinea favosa, tinea alba, black-dot ringworm and kerion. Clinically an inflammatory or noninflammatory alopecia occurs. Epidemiology The true inci

19、dence of tinea capitis is unknown. The patients most commonly affected are children between the ages of 4 and 14 years. The disease can also be transmitted from child to child through exposure at schools or day-care centers. Affected hairs can harbor infectious organisms for a year or more after the

20、y have been shed from the host. Etiology and pathogenesis Tinea capitis can be caused by all the pathogenic dermatophytes except for E.floccosum and T. concentricum. Tinea favosa T. shoenleinii Tinea alba M. canis, M. gypseum, occasional M. ferrugnineum. Black-dot ringworm-T. violaceum、T. tonsurans、

21、T. mentagrophytes. Kerion Zoophilic or geophilic dermatophytes (ie M. canis 、M. gypseum、 T. mentagrophytes) Ectothrix infection: It usually begins in the perifollicular stratum corneum. Following a period of incubation, hyphae generally spread into and around the hair shaft. They descend into the fo

22、llicle and penetrate the midportion of the hair. Subsequently, hyphae descend within the intrapilary portion of the hair Intrapilary hyphae proliferate and divide into arthroconidia that reach the cortex of the hair and are transported upward on its surface. The numerous ectothrix spores are seen, r

23、ather than the intrapilar hyphae. Endothrix infections: the same process occurs until the hair is penetrated. The arthroconidia are formed rapidly and in time replace much of the intrapilary keratin. The hair is fragile and breaks at its weakest point of the surface of the scalp. The remaining hair

24、in this infected follicle resembles a black dot. Clinical manifestations The different tinea capitis caused by organisms may present with several different clinical patterns. 1. tinea favosa It is very rare at present. It appears chiefly upon the scalp, but may offer the glabrous skin and the nails.

25、 In the early stages of infection (within the first 3 weeks of infection), a light amount of perifollicular scaling、 perifollicular inflammatory and papular and pustuler are seen at the root of hair Scutula : From a yellowishred papule to form a yellowish、cupshaped structure, l cm or more in diamete

26、r. Its center is pierced by a single or several、lusterless、dry hairs. In a patchy distribution on the scalp and coalesce. The infected area becomes extensively scarred and almost totally devoid of hair. There is a distinctive mousy odor. In later stages of infection, a cicatricial alopecia may be pr

27、esent. Besides scalp involvement, favus may involve glabrous skin and nails. Tinea favosa 2. Tinea alba (microsporia capitis) The patients most commomly affected are children between the ages of 4 and 14 years. Tinea alba present as the classic form of noninflammatory tinea capitis, characterized by

28、 multiple scaly lesions (“grey-patch”), stubs of broken hair, and a minimal inflammatory response. The hairs break off a few millimeters above the surface. The remaining hair shaft is surrounded with greyish-white scales (a sheath of ting spores). The patients with tinea alba may spontaneously heal

29、when they reach the ages of puberty. The subjective symptom is very light pruritus. Tinea alba 3. Black-dot ringworm caused by endothrix organisms. affect adults and children. multiple areas of alopecia studded with black dots ( infected hairs broken off at or below the surface of the scalp) diffuse

30、 scaling with minimal hair loss and inflammation. located on the vertex and occiput. The course of black-dot ringworm is chronic. When the disease is untreated, the process may last for years. It may also be quite inflammatory, so it may be followed by scarring and permanent alopecia in the areas of

31、 inflammation and suppuration. Black-dot ringworm 4. Kerion Kerion is an inflammatory type. It is caused most commonly by zoophilic organism (e.g. M.canis) or geophilic dermatophytes （e.g. M.gypseum）. This inflammatory reaction is felt to be a delayed type hypersensitivity reaction to fungal element

32、s. scaly, erythematous, papular eruption with loose and broken off hairs varying degree of inflammation (from a pustular folliculitis to an inflammatory boggy mass stubbed with broken hairs, oozing purulent material from follicular orifices) A tender (soft) consistency is sensed,and tenderness is ve

33、ry obvious. These infectious usually present with pruritus, fever and pain. There may be associated regional lymphadenopathy. Kerion may be followed by scarring and permanent alopecia. Kerion Laboratory examination 1. Woods light examination the skin faintly blue tinea alba bright green black dot ri

34、ngworm not fluoresce tinea favora dull green. 2. Mycologic examination 1) Microscopic examination: Tinea favosa: scutulaehyphea , spores hairarthrospores and bubbles of air inside the hair shaft Tinea alba: ectothrix type (a sheath of tiny spores) Black-dot ringworm: endothrix type (arthrospores ins

35、ide the hair shaft) 2) Culture procedure The exact identification of the causative fungus may be determined by culture. The clinical specimens are planted upon Sabourauds glucose agar, 25, for 3-5 days to grow, about 1 week to determine the identification of the fungus. Diagnosis Differential Diagno

36、sis Diagnosis criteria: 1) clinical features 2) laboratory examination: woods light microscopic examination culture. Differential diagnosis: Tinea capitis must be differentiated from seborrheic dermatitis, lichen simplex chronicus, alopecia areata, psoriasis, trichotillomania, and other inflammatory

37、 follicular conditions. Treatment “5-word” remedy: depilating washing taking medicine applying the external agents sterilizing 1. Depilating once weekly for 3times 2. Washing once daily 3. Taking medicine Tinea capitis requires a systemmic oral antifungal. Systemic administration of griseofulvin pro

38、vided the first effective oral therapy for tinea capitis. Newer antifungal medications, such as itraconazole and terbinafine are used most commonly. 1) Griseofulvin: griseofulvin of ultramicronized form, 15-20mg/kg/d, for continued for 2-4 months, or for at least two weeks after negative microscopic

39、 and culture examination 2) Itraconazole: 5mg/kg/d for 6w; or applying pulse therapy ( 200mg bid for 1 week per month for 3 consecutive months) 3) Terbinafine: for the body weight 25kg, 250mg/d for 6weeks; for the body weight 18.5-25kg, 125mg/d for 6weeks; for the body weight 18.5kg， 62.5mg/d for 6

40、weeks. The above three medications are fat- soluble, so they are administered after meal. A higher incidence of hepatotoxicity must be noted during long-term therapy. In ectothrix infection (e.g.M.audouinil, M.canis), a longer duration of therapy may be required. 4) Oral steroids may help reduce the

41、 risk and extent of permanent alopecia in the treatment of kerion. Avoid using topical corticosteroids during treatment of dermatophyte infections. 4. Topical treatment Only topical treatment usually is ineffective. Adjunct therapy with topical antifungal agents is also advisable. 5-10% sulfur ointm

42、ent terbinafin cream x 2 consecutive months Shampoos containing antifungal agents once daily for 15 minutes x 2 months Tinea pedis and Tinea manus Tinea pedis is a dermatophyte infection of the feet. Tinea manus is a dermatophyte infection of the palmar and interdigital areas of the hand, occasional

43、 spreading the dorsum of the hand. Only the dermatophyte infection of the dorsum is called tinea corporis. Epidemiology Approximately l0 percent of the total population have a dermatophyte foot infection. In athletic teams, military organizations and boarding schools, the rate of infection is much h

44、igher. The infection is common during the summer months and in tropical or semitropical climates. Etiology Tinea pedis and tinea manus are caused most commonly by T.rubrum (50%-90%), next T.mentagrophytes or E.floccosum. T.rubrum commonly produces a dry, hyperkeratotic, moccassin-like involvement of

45、 the feet and/or hands. T.mentagrophytes often produces a vesicular pattern. E.floccosum may produce either of the two patterns described above. Clinical manifestations (1) Tinea pedis Tinea pedis is divided into four types: vesicular type intertriginous type scaly hyperkeratosis type acute ulcerati

46、ve variant 1) Vesicular type Causative organism: T.mentagrophytes Predilection sites: interdigitale, the midanterior plantar surface and near the instep, even the entire sole. The vesicles are deep, usully about 2or 3 mm in diameter. They sometimes coalesce to form bullae of various sizes. They are

47、firm, and do not rupture spontaneously but dry up as the acute stage subsides, leaving yellowish brown crusts. The vesicles contain a clear tenacious fluid of the consistency of glycerin. The burning and itching cause great discomfort. This discomfort is relieved by opening the tense vesicles. The f

48、issures and the vesicles may become secondarily infected with pyogenic cocci. This may lead to recurrent attacks of lymphangiitis , erysipelas and inguinal adenitis. Tinea pedis: Vesicular type 2) Intertriginous type This type is the most common. It is characterized by maceration, slight scaling and

49、 occasional vesiculation and fissures in the interdigital or subdigital areas. The lateral (i.e. 4th to 5th or 3rd to 4th) toe webs are the most common sites of infection. Infection may spread to the sole or instep of the foot but seldom involves the dorsum. The patients feel itching or painful fiss

50、uring. there may be an overgrowth of gram- negative organisms. This may eventuate in an ulcerative, exudative process. Tinea pedis: intertriginous type 3) Scaly hyperkeratosis type Causative organisms: T.rubrum and occasionally T.mentagrophytes They produce a noninflammatory type. This type may invo

51、lve the entire sole and the sides of the foot. It is characterized by a dull erythema, hyperkeratosis, and pronounced scaling. It may be limited to one hand and both feet. This observation is still awaiting an explanation. Tinea pedis: scaly hyperkeratosis type 4) Acute ulcerative variant This patte

52、rn is commonly associated with a grouped vesicular, maceration, weeping denudation and ulceration of sizable areas of the sole of the foot. Obvious white hyperkeratosis and pungent odor are characteristically present. This infection is often complicated by a secondary bacterial (often gram- negative

53、)overgrowth. This may lead to cellulitis,lymphangiitis and lymphadenitis. (2) Tinea manus The incidence of tinea manus is lower than that of tinea pedis. Its lesions is similar to that of tinea pedis. But intertriginous type is very rare except infections of candida. The clinical features are mostly

54、 vesicular type and scaly hyperkeratosis type. Tinea manus Laboratory examination (1) Microscopic examination: When the lesion is a vesicle, it is clipped off close to the margin by small pointed scissors; When the lesion is dry or scaly, the material is scraped off with a scalpel or curet, an effor

55、t being made especially to obtain material from deep beneath the surface of chronic eruptions. A drop of a 10 to 20 percent solution of potassium hydroxide is added to the material on the glass slide. A coverslip is placed over the specimen. Gentle heat is applied until the scales are thoroughly mac

56、erated. The both hyphae and spores is seen (2) Culture The other portion of the material is planted on Sabourauds glucose agar at room temperature. Adequate growth for identification occurs in 5 to 14 days, depending upon the kind of fungus. Diagnosis and Differential Diagnosis Diagnosis 1) clinical

57、 features 2) mycologic examinations Differential diagnosis: Tinea manus is frequently difficult to differentiate from allergic contact or irritant dermatitis, especially occupational, or from pompholyx, atopic dermatitis, or psoriasis. In the scaly hyperkeratotic variety of tinea pedis, confusion ca

58、n occur with diseases such as psoriasis, hereditary or acquired keratodermas of the palms and soles, pityriasis rubra pillars. In the vesicular or vesiculopustular presentation, tinea pedis can be confused with pustular psoriasis, pustulosis palmaris et plantaris, and bacterial pyodermas. Prevention

59、 and treatment (1) Topical therapy The topical therapy is a main therapy for tinea pedis and tinea manus. The treatment is selected a according to the clinical presentation and disease severity. Intertriginous type powder (undecylenic acid or tolnaftate powder) Vesicular type liniment (5% salicylic

60、acid solution, Castellanis paint) Scaly hyperkeratosis type ointment and emulsion(5-10%salicylic acid ointment, clotrimazole、miconazole 、 econazole cream, etc) Acute ulcerative variant solution (wet dressing) (1/5000 pottasium permanganate solution. 0.1% rivanol solution) Complicated eczema firstly