Fungal Skin Infection - PDF

Department of Dermatology DR Hanaa haydar Fungal Skin Infection General knowledge of the fungi Yeast : unicellular, 370C Mold : multicellular, hyphae, 250C Dimorphic fungi (thermally dimorphic fungi) : mold--------yeast Superficial mycoses There are a number of fungi capable of infec...

Department of Dermatology DR Hanaa haydar Fungal Skin Infection General knowledge of the fungi Yeast : unicellular, 370C Mold : multicellular, hyphae, 250C Dimorphic fungi (thermally dimorphic fungi) : mold--------yeast Superficial mycoses There are a number of fungi capable of infecting various superficial structure, including hair, nails, stratum corneum of the skin(Dermatophytoses ) Dermatophytes ecology Classified in to 3 categories Geophilic : normally live in soil Zoophilic : primarily parasitize the body surfaces of animals but can transmitted to humans (T.mentagrophytes, M.canis) Arthropophilic : generally infect humans and are transmitted between individuals Dermatophytosis Dermatophytosis (tinea or ringworm) is the infection of keratinized structures, including the nails, hair shafts, and stratum corneum of the skin, by organisms of three species of fungi termed the dermatophytes ; Trichophyton(skin hair nail) Epidermophyton(skin nail) Microsporum(skin hair) Dermatophyte involvement progresses in a centrifugal manner with central clearing (hence named ringworms). Various clinical forms are as under: Tinea** capitis (scalp) Tinea barbae (beard and moustache) Tinea faciei (face) Tinea corporis (body) Tinea cruris (groins) Tinea manuum (hands) Tinea pedis (feet) Tinea unguium (nails) Tinea incognito Con-Tinea corporis All dermatophytes can produce lesion to glabrous skin eg.T.rubrum ,T.mentagrophyte M.canis..etc. Typical lesion annular rasied edge (active border) covered with minute papules ,vesicles,pustules,and clearing center Tinea Corporis (ringworm of the body) Tinea corporis caused by M. canis following contact with infectious kittens3  clinical variants of tinea corporis. 1-Circinate typical lesion 2-Tinea gladiatorum — affects participants in contact sports such as wrestling or martial arts due to skin-to- skin contact. It is usually caused by T. tonsurans. 3-Tinea imbricata — concentric rings forming polycyclic plaques with thick scale 4-Tinea incognito — lacks the typical features after applying topical steroid 5-majocchi granuloma— (Nodular perifolliculitis ) Perifollicular inflammation and follicular pustules on the leg due to Trichophyton rubrum T.imbricata ‘Tinea incognito’. Topical steroid applications have thinned the skin and altered much of the morphology. A recognizable active spreading edge is still visible. Majocchi granuloma Tinea cruris Its dermatophytosis of the groin. Site: upper medial side of the thigh extend to buttocks and pubic area rarely involve scrotal(in contrast to candidiasis) Predisposing factors: Worm and moist weather /sweating/diabetes Tinea Cruris (Jock itch) Infection of the groin, mainly seen in men Tinea Capitis non-inflammatory and inflammatory variants. Non-inflammatory variants Gr ey patch(Ectothrix)(scaly tinea captis)(M.canis and M.audonii) single or multiple round or oval patches of partial alopecia covered with small grayish white scales. Black dot(Endothrix ): hair break of at the surface of the scalp resulting in (black dot)  inflammatory variants 1-Kerion: dermatophytes of animal origin are most common cause.(eg.T.verrucosum) result from inflammatory reaction with boggy swelling raised over the surface of the scalp. 2-Favus:(T.schoenleinii) (sever)characterized by scutula yellow cup-shaped crust and( hyphae , air spaces) are observed within the hair shaft, and a bluish-white fluorescence. Black dot Favus ( Dermatophytid “id” reaction In cases of inflammatory tinea capitis, widespread “id” eruptions may appear concomitantly on the trunk and extremities. These are vesicular, lichenoid, papulosquamous, or pustular and represent a systemic reaction to fungal antigens Most common lesions on hands/lateral fingers They typically clear rapidly after treatment of the fungal infection Dermatophytid “id” reaction Tinea Barbae Tinea Manuum Zoophilic dermatophyte infections of the face have classic features e.g. scale, annular configuration, pustules in the border Usual cause is sleeping with a pet with zoophilic infection. Tinea Barbae seen in ranchers, farmers, animal handlers (i.e., from zoophilic species acquired from cattle,dogs, etc.) T.mentagrophytes and T. verrucosum CF; ntense inflammation and multiple follicular pustules kerion Tinea Pedis or athlete’s foot Caused by anthropophilic fungi T.rubrum or T.mentagrophytes var. interdigitale Usually seen with scaling and maceration and itching between the toes, particularly the fourth interdigital space.  clinical types of Tinea pedis 1- interdigital :scaling ,fissuring or erythema of the web spaces between the toes (3rd and4th) toe clefts 2-hyperkeratotic (moccasin-type):scaling of planters surface and sides of feet 3-vesiculobullous (T.mentagrophytes)pruritic tense vesicles and bullae affect the whole soles. Moccasin type  Tinea pedis caused by T. rubrum. Sub-clinical infection (left) showing mild maceration under the little toe and more severe infection showing extensive maceration of all toe web spaces 3 Tinea is transmitted via the feet by desquamated skin scales in substrates like carpet and matting. 3 3 http://www.mycology.adelaide.edu.au/Mycoses/Cutaneous/Dermatophytosis/index.html Tinea Unguium (dermatophyte onychomycosis) usually caused by Trichophyton sp.  Tinea Unguium It can present as several different patterns:. Distal and lateral Subungual onychomycosis. The end of the nail lifts up. The free edge often crumbles.(T.rubrum) Superficial white onychomycosis. Flaky white patches on the top of the nail plate. (T.mentagrophyte ,aspergiius,fusarium,acremnium) Proximal white Subungual onychomycosis. (HIV)  Complications Fierce animal ringworm of the scalp can lead to a permanent scarring alopecia.. Epidemics of ringworm occur in schools. The usual appearance of a fungal infection can be masked by mistreatment with topical steroids(tinea incognito)  Differential diagnosis Area Differential diagnosis Scalp Alopecia areata, psoriasis, seborrhoeic eczema, carbuncle, abscess Feet Erythrasma, eczema Trunk Discoid eczema, psoriasis, candidiasis, pityriasis rosea Groin Candidiasis, erythrasma, irritant and allergic contact dermatitis, psoriasis, neurodermatitis Nails Psoriasis, paronychia, trauma, ageing changes Hand Chronic eczema, xerosis, investigations Microscopic examination of a skin scraping nail clipping or plucked hair in KOH mount Cultures Wood’s light (ultraviolet light) examination of the scalp usually reveals a green fluorescence of the hairs.(pteridine) Treatment Local Imidazole preparations (e.g. Miconazole & and Clotrimazole and ketoconazole) tiwice daily in T.pedis Terbinafine Applied twice daily Amorolfine and Tioconazole nail solutions  systemic Terbinafine 250mg once daily for 2weeks(tinea cruris/corporis/pedis) Itraconazole cap 100mg 2caps daily for 7days Griseofulvin 12,5mg/kg for 2-4weeks in tinea cruris/corporis and for 6-8 weeks in capitis Pityriasis (Tinea) Versicolor This is a chronic, superficial fungal disease of the skin. Caused by lipophilic yeast Malassezia furfur and Malassezia globosa There are at least six different Malassezia species recognized only recently. Clinical features The lesions are asymptomatic small hypopigmented or hyperpigmented macules. Most common site : back, underarm, uppe r arm, chest, neck Most common in adolescent and young adult males Associated with hot & humid climate and increased sweating.  Pityriasis versicolor showing hyperpigmented lesions in a Caucasian and hyphopigmented lesions in an Australian Aborigine 1 1 http://www.mycology.adelaide.edu.au/Mycoses/Superficial/Malassezia_infections/index.html Culture of Malassezia furfur on Dixon's agar (contains glycerol mono-oleate) Diagnosis - Clinical :- asymptomatic, hypopigmented or discolored macules with fine dust-like scaling. - Involving upper trunk, neck, and arms. - KOH smear showing typical findings. ( spaghetti and meatballs appearance ). - Wood lamp examination (yellow-orange) Treatment - Anti-fungal cream, lotion, or shampoo are usually effective ( ketoconazole , terbinafine and selenium sulphate. How ever skin discoloration may last for weeks to months. Candidiasis of skin, mucous membranes and nails Predisposing factors Infancy, pregnancy, old age Disorders of immune function, e.g., leukemia, corticosteroid therapy. Chemotherapy, e.g., immunosuppressive, antibiotic Endocrine disease, e.g., diabetes mellitus Carcinoma Commensal becomes pathogenic in presence of following predisposing factors: Diabetes Other Antibiotics endocrine. candidias Obesity (friction) is Immersion in water Poor hygiene Pregnancy Oral High humidity, contraceptive Occlusive clothes Oropharyngeal candidiasis : including thrush, glossitis, stomatitis and angular cheilitis (perle che) Oral thrush  Candidiasis of skin, mucous membranes and nails Cutaneous cadidiasis : including intertrigo, diaper candidiasis, paronychia and onychomycosis Interdigital candidiasi s Candidia onychomycosis and paronychia4 4 http://dermis.multimedica.de/doia/image.asp?zugr=d&lang=e&cd=36&nr=59&diagnr=112301#0 Investigations KOH mount shows budding yeast and pseudohyphae Swabs from suspected areas for culture Urine for sugar In chronic mucocutaneous candidiasis Detailed immunological work-up Treatment Predisposing factors should be sought and eliminated Infected skin folds should be separated and kept dry Chronic paronychia -keep their hands warm and dry Topical nystatin and the azole group of compounds are effective and topical or oral antibiotic if associated infection. Oral suspensions and oral gels for oral lesions. Imidazole pessaries or topical azoles for genital lesion.  Erythrasma /Candiasis ???? 1 cause 2 clinical presentation 3 wood lamp 4 Koh 5 Treatment Antifungal therapy Classification of systemic antifungals according to the site of action 1- At the nuclear level (flucytosine ): Flucytosine its converted to 5 fluorouracil which interferes with nucleic acid synthesis (RNA&DNA) 2-At cell membrane level(synthesis or function): A-Allylamines (naftifine –terbinfine) inhibition of squalene epoxidase with fungel growth arrest(fungistatic) this leads also to aqualene accumulation within the fungel cell with its death(fungicidal_) Con-classification B-Azoles (imidazole and triazoles):( inhibibition of cytochrome p450 14-α demethylase) disrupt ergosterol biosynthesis. Imidazole:(clotrimazole,ketoconazole,miconazole) Triazoles:(Itraconazole,fluconazole,voriconazole) #different between them in the mechanism of inhibition of cyp450 C-polyenes (Nystatin ,AmphotericinB) They bind with ergosterols irrevribley altered celluler permeability with leakage of celluler content and cell death  Con-classification 3- At the level 0f cell wall : Echinocandins(caspofungin ,micafungin) It inhibit the synthesis of β-(1,3)-D-glucan synthase. 4-Act on mitotic spindle: Griseofulvin bind and interferes with the function of spindle and cytoplasmic microtubles Thank you for your kind patience……