Cutaneous Fungal Infections

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my presentation in dermatology posting when i was a house surgeon

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Cutaneous Fungal Infections:

Cutaneous Fungal Infections Dermatophytosis - "ringworm" disease of the nails, hair, and/or stratum corneum of the skin caused by fungi called dermatophytes. Dermatomycosis - more general name for any skin disease caused by a fungus.

THE SKIN PLANTS:

THE SKIN PLANTS Dermatophytes are keratinophilic - "keratin loving".  Keratin is a major protein found in horns, hooves, nails, hair, and skin. Ringworm - disease called ‘herpes' by the Greeks, and by the Romans ‘tinea' (which means small insect larvae).

Dermatophytes:

Dermatophytes Taxonomic classification They belong to the phylum Deuteromycota (Fungi Imperfecti) They are hyaline moulds (transparent / white) Three genera comprise this group Microspourm Trichophyton Epidermophyton

Infections by Dermatophytes:

Infections by Dermatophytes Severity of ringworm disease depends on (1) strains or species of fungus involved and (2) sensitivity of the host to a particular pathogenic fungus. More severe reactions occur when a dermatophyte crosses non-host lines (e.g., from an animal species to man).  Among dermatophytes there appears to be a evolutionary transition from a saprophytic to a parasitic lifestyle. Geophilic species - keratin-utilizing soil saprophytes (e.g., M. gypseum , T. ajelloi ). Zoophilic species - keratin-utilizing on hosts - living animals (e.g., M. canis , T. verrucosum ). Anthropophilic species -  keratin-utilizing on hosts - humans (e.g., M. audounii , T. tonsurans )

Geographic Distribution:

Geographic Distribution Worldwide

Dermatophytes 3 Genera:

Dermatophytes 3 Genera Trichophyton Microsporum Epidermophyton

Trichophyton (19 species):

Trichophyton (19 species) Hair Skin Nails

Trichophyton species:

Trichophyton species Large, smooth, thin wall, septate, pencil-shaped

Trichophyton tonsurans:

Trichophyton tonsurans http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Dermatophytes/Trichophyton/tonsurans.html

Trichophyton rubrum:

Trichophyton rubrum Common dermatophyte

Microsporum (13 species):

Microsporum (13 species) Skin Hair

Microsporum species:

Microsporum species Thick wall, spindle shape, multicellular

Microsporum canis:

Microsporum canis . Most common etiologic agent of tinea in SC whites

Epidermophyton floccosum:

Epidermophyton floccosum Skin Nails

Epidermophyton floccosum:

Epidermophyton floccosum Bifurcated hyphae with multiple, smooth, club shaped macroconidia (2-4 cells)

Clinical manifestations of ringworm infections are called different names on basis of location of infection sites:

Clinical manifestations of ringworm infections are called different names on basis of location of infection sites tinea capitis - ringworm infection of the head, scalp, eyebrows, eyelashes tinea favosa - ringworm infection of the scalp (crusty hair) tinea corporis - ringworm infection of the body (smooth skin) tinea cruris - ringworm infection of the groin (jock itch) tinea unguium - ringworm infection of the nails tinea barbae - ringworm infection of the beard tinea manuum - ringworm infection of the hand tinea pedis - ringworm infection of the foot (athlete's foot)

Species found in different anamorphic genera are the cause of different clinical manifestations of ring worm:

Species found in different anamorphic genera are the cause of different clinical manifestations of ring worm Microsporum - infections on skin and hair (not the cause of TINEA UNGUIUM) Epidermophyton - infections on skin and nails (not the cause of TINEA CAPITIS) Trichophyton - infections on skin, hair, and nails.

Major sources of ringworm infection :

Major sources of ringworm infection Schools, military camps, prisons. Warm damp areas (e.g., tropics, moisture accumulation in clothing and shoes).  Historical note:  More people were shipped out of the Pacific Theater in WWII back to U.S. because of ringworm infection then through injury. Animals (e.g., dogs, cats, cattle, poultry, etc.).

TINEA CAPITIS:

TINEA CAPITIS Tinea capitis is a disease caused by superficial fungal infection of the skin of the scalp, eyebrows, and eyelashes, with a propensity for attacking hair shafts and follicles. The disease is considered to be a form of superficial mycosis or dermatophytosis

Pathophysiology :

Pathophysiology Tinea capitis is caused by fungi of species of genera Trichophyton and Microsporum

PowerPoint Presentation:

Three types of in vivo hair invasion are recognized. Ectothrix invasion is characterized by the development of arthroconidia on the exterior of the hair shaft. The cuticle of the hair is destroyed, and infected hairs usually fluoresce a bright greenish-yellow color under a Wood lamp ultraviolet light. Common agents include Microsporum canis, Microsporum gypseum, Trichophyton equinum, and Trichophyton verrucosum. Endothrix hair invasion is characterized by the development of arthroconidia within the hair shaft only. The cuticle of the hair remains intact and infected hairs do not fluoresce under a Wood lamp ultraviolet light. All endothrix-producing agents are anthropophilic (eg, Trichophyton tonsurans, Trichophyton violaceum ). Favus , usually caused by T schoenleinii, produces favus like crusts or scutula and corresponding hair loss .

Ectothrix and Endothrix:

Ectothrix and Endothrix Fluorescing hair (under Wood's lamp) is seen in dogs and cats infected with some dermatophytes

Gray-patch ringworm (microsporosis) is an ectothrix infection:

Gray-patch ringworm (microsporosis) is an ectothrix infection

Typical lesions of kerion Note numerous bright yellow purulent areas on skin surface, surrounded by adjacent edematous, erythematous, alopecic areas:

Typical lesions of kerion Note numerous bright yellow purulent areas on skin surface, surrounded by adjacent edematous, erythematous, alopecic areas

Favus :

Favus

HISTORY:

HISTORY Tinea capitis begins as a small erythematous papule around a hair shaft on the scalp, eyebrows, or eyelashes. Within a few days, the red papule becomes paler and scaly, and the hairs appear discolored, lusterless, and brittle. They break off a few millimeters above the scalp skin surface. The lesion spreads, forming numerous papules in a typical ring form.  Ring-shaped lesions may coalesce with other infected areas. Pruritus usually is minimal but may be intense at times. Alopecia is common in infected areas. Inflammation may be mild or severe. Deep boggy red areas characterized by a severe acute inflammatory infiltrate with pustule formation are termed kerions or kerion cels

PowerPoint Presentation:

Pertinent physical findings are limited to the skin of scalp, eyebrows, and eyelashes. Primary skin lesions of tinea capitis Lesions begin as red papules with progression to grayish ring-formed patches containing perifollicular papules. Pustules with inflamed crusts, exudate, matted infected hairs, and debris may be seen. Black dot tinea capitis refers to an infection with fracture of the hair, leaving the infected dark stubs visible in the follicular orifices. Kerion celsi may progress to a patchy or diffuse distribution and to severe hair loss with scarring alopecia Boggy fungating swelling with easily pluckable hair in a child think tinea capitis.

Discrete patches of hair loss or alopecia:

Discrete patches of hair loss or alopecia

Differential Diagnoses:

Differential Diagnoses PYODERMA ALLOPECIA AREATA LUPUS ERYTHEMATOSIS SYPHILLIS PSORIASIS Seborrheic dermatitis Impetigo

Diagnosis:

Diagnosis Note the symptoms. Microscopic examination of slides of skin scrapings, nail scrapings, and hair.  Often tissue suspended in 10 % KOH solution to help clear tissue.  Slides prepared this way are not permanent.  These degrade rapidly due to presence of base. Isolation of the fungus from infected tissue . Definitive diagnosis depends on an adequate amount of clinical material submitted for examination by direct microscopy and culture. The turn-around time for culture may take several weeks . Culture provides precise identification of the species . Primary isolation is carried out at room temperature, usually on Sabouraud agar containing antibiotics (penicillin/streptomycin or chloramphenicol) and cycloheximide, which is an antifungal agent that suppresses the growth of environmental contaminant fungi.

PowerPoint Presentation:

Wood lamp examination- Hairs infected by M canis , M audouinii , M rivalieri, and M ferrugineum fluoresce a bright green to yellow-green color . Hairs infected by T schoenleinii may show a dull green or blue-white color, and hyphae regress leaving spaces within the hair shaft. T verrucosum exhibits a green fluorescence in cow hairs, but infected human hairs do not fluoresce. The fluorescent substance appears to be produced by the fungus only in actively growing infected hairs.

Microsporum canis infection, scalp hairs emit a diagnostic brilliant green fluorescence.:

Microsporum canis infection, scalp hairs emit a diagnostic brilliant green fluorescence.

Dermatophyte Culture:

Dermatophyte Culture

Dermatophyte Culture:

Dermatophyte Culture

Dermatophyte Culture:

Dermatophyte Culture

Tinea Capitis:

Tinea Capitis Gray Patch

Trichophyton schoenleinii:

Trichophyton schoenleinii http://www.mycology.adelaide.edu.au/Fungal_Descriptions/Dermatophytes/Trichophyton/schoenlenii.html

Treatment :

Treatment Griseofulvin has been the treatment of choice in all ringworm infections of the scalp . Dose of 20-25 mg/kg/d for 6-8 weeks. Griseofulvin accumulates in keratin of the horny layer, hair, and nails, rendering them resistant to invasion by the fungus .Treatment must continue long enough for infected keratin to be replaced by resistant keratin, usually 4-6 weeks

PowerPoint Presentation:

Several newer antimycotic agents, including itraconazole, terbinafine, and fluconazole, have been reported as effective and safe.

PowerPoint Presentation:

In inflammatory lesions, compresses often are required to remove pus and infected scale

PowerPoint Presentation:

Terbinafine tablets at doses of 3-6 mg/kg/d for approximately 2-4 weeks Fluconazole tablets or oral suspension (3-6 mg/kg/d) are administered for 6 weeks. Although oral ketoconazole also is an acceptable alternative to griseofulvin, it is not considered a treatment of choice because of the risk of hepatotoxic effect and higher cost. Treatment for the deep folliculitis seen in Majocchi granuloma is systemic oral antifungal therapy.

PowerPoint Presentation:

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