Only skin and nails are affected in
Ans. c (Epidermophyton floccosum) (Ref. Textbook of microbiology by Ananthanarayan 6th ed., 567)DERMATOPHYTOSISType of MycosisCausative Fungal AgentsMycosisSuperficialMalassezia speciesTinea nigraTrichosporon speciesPiedraia hortaePityriasis versicolor;Hortaea werneckiiWhite piedraBlack piedraCutaneousMicrosporum species, Trichophyton species, and Epidermophyton floccosumCandida albicans and other Candida speciesDermatophytosisCandidiasis of skin, mucosa, or nailsSubcutaneousSporothrix schenckiiPhialophora verrucosa, Fonsecaea pedrosoi, othersPseudallescheria boydii, Madurella mycetomatis, othersExophiala, Bipolaris, Exserohilum, and othersSporotrichosisChromoblastomycosisMycetomaPhaeohyphomycosis# Dermatophytes are fungi that infect skin, hair, and nails and include members of the genera Trichophyton, Mi- crosporum, and Epidermophyton.# Any dermatophyte can cause tinea corporis (annular scaly patches with raised, erythematous vesicular borders and central clearing).# Tinea faciei, like tinea corporis, can be caused by any dermatophyte. T. rubrum and E. floccosum are common causes of tinea cruris; similar lesions can be caused by Candida infection.# Tinea pedis is the most common clinical dermatophytic infection. The most common cause of tinea pedis is T. rubrum.# Tinea nigra is a rare infection of the palms caused by the dematiaceous fungus Hortaea (formerly Exophiala) werneckii. Two types of piedra characterized by nodules of fungal elements on the hair shaft have been reported:- Black Piedra caused by Piedraia hortae and- White Piedra caused by Trichosporon species.# Tinea unguium is caused by T. rubrum, T. mentagrophytes, and E. floccosum. Dermatophytes cause 80-90% of cases of onychomycosis.# Tinea capitis is a common dermatophytic disease of children. Hair may break off at the scalp ("black-dot ringworm"). Inflammatory responses may be minimal or severe, with the formation of a KERION characterized by alopecia, a tender or painful boggy scalp, purulent drainage, and localized lymphadenopathy. T. tonsurans is the most common dermatophyte associated with tinea capitis.# T. beigelii has historically been the most significant pathogen in the genus Trichosporon.# The diagnosis of tinea can be made from skin scrapings, nail scrapings, or hair by culture or direct microscopic exam with KOH or by nail PAS stain.Dermatophytic Skin DiseaseLocation of LesionsClinical featuresFungi most frequently responsibleTinea corporis(ringworm)Nonhairy, smooth skin.Circular patches with advancing red, vesiculated border and central scaling.Pruritic.T rubrum, E floccosumTinea pedis(athlete's foot)Interdigital spaces on feet of persons wearing shoes.Acute: itching, red vesicular. Chronic: itching, scaling, fissures.T rubrum, T mentagrophytes, E floccosumTinea cruris(jock itch)Groin.Erythematous scaling lesion in intertriginous area.Pruritic.T rubrum, T mentagrophytes; E floccosumTinea capitisScalp hair. Endothrix: fungus inside hair shaft. Ectothrix: fungus on surface of hair.Circular bald patches with short hair stubs or broken hair within hair follicles.Kerion rare.Microsporum-infected hairs fluoresce.T mentagrophytes, M canisTinea barbaeBeard hair.Edematous, erythematous lesion.T mentagrophytesTinea unguium(onychomycosis)Nail.Nails thickened or crumbling distaliy; discolored; lusterless.Usually associated with tinea pedis.T rubrum, T mentagrophytes, E floccosumDermatophytid(id reaction)Usually sides and flexor aspects of fingers.Palm. Any site on body.Pruritic vesicular to bullous lesions.Most commonly associated with tinea pedis.No fungi present in lesion.May become secondarily infected with bacteria.Dermatophytosis: Treatment# Topical imidazoles, triazoles, and allylamines may be effective therapies for dermatophyte infections, but nystatin is not active against dermatophytes.# Oral antifungal agents may be required for recalcitrant tinea pedis or tinea corporis, those involving the hair and nails.# Griseofulvin- is the only oral agent approved for dermatophyte infections involving the skin, hair, or nails.- Griseofulvin administered with a fatty meal is an adequate dose for most dermatophyte infections.- The usual adult dose of griseofulvin for tinea capitis is 1 g microsized or 0.5 g ultramicrosized given daily.- The duration of therapy may be# 2 weeks for uncomplicated tinea corporis,# 8-12 weeks for tinea capitis, or as long as# 6-18 months for nail infections.- Common side effects of griseofulvin include# Headache# Urticaria# Gastrointestinal distress# Oral itraconazole and terbinafine are approved for onychomycosis.Clinical FeaturesEtiologic AgentTreatment ImpetigoHoney-colored crusted papules, plaques, or bullaeGroup A Streptococcus and Staphylococcus aureusSystemic or topical antistaphylococcal antibioticsDermatophytosisInflammatory or noninflammatory annular scaly plaques; may have hair loss; groin involvement spares scrotum; hyphae on KOH preparationTrichophyton, Epidermophyton, or Microsporum sp.Topical azoles, systemic griseofulvin, terbinafine, or azolesCandidiasisInflammatory papules and plaques with satellite pustules, frequently in intertriginous areas; may involve scrotum; pseudohyphae on KOH preparationCandida albicans and other Candida speciesTopical nystatin or azoles; systemic azoles for resistant diseaseTinea versicolorHyperpigmented or hypopigmented scaly patches on the trunk; characteristic mixture of hyphae and spores on KOH preparation ("spaghetti and meatballs")Malassezia furfurTopical selenium sulfide lotion or azoles
Microspora gypseum
Microspora audovinii
Epidermophyton floccosum
Tricophyton rubrum
Fungal Infection