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Superficial Fungal Infections:Dermatophytes Part 1

Glenn D. Roberts, PhD

Division of Clinical Microbiology

Department of Laboratory Medicine & Pathology

Mayo Clinic

Rochester, Minnesota

2012 Mayo Foundationfor Medical Educationand Research. All rights reserved.

Superficial Fungal Infections: Dermatophytes Part 1

Disclosures

None



Selection of Clinical Specimens

Normal Host Hair

Skin

Nails

Immunocompromised host

Potentially any source


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Microbiology

Trichophyton

Characterized by macroconidia that are elongated,

pencil to cigar-shaped, smooth-walled, multiseptate,and thin-walled

In general, microconidia predominate in most cultures

They may be arranged in clusters, produced singly alonghyphae, or hardly sporulate at all




Genus Trichophyton


Microbiology

Epidermophyton

Produces only large, multiseptate, smooth-walled,and club-shaped macroconidia

Microsporum

Characterized by large, multiseptate, rough-walled,and spindle-shaped macroconidia


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Genus Epidermophyton



Genus Microsporum


Common Dermatophytes Foundin North America

Trichophyton rubrum T mentagrophytes

T tonsurans

T verrucosum

Microsporum canis M audouinii

Epidermophytonfloccosum


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Ecology

Anthropophilic

Trichophyton mentagrophytes

Trichophyton rubrum

Trichophyton tonsurans

Epidermophyton floccosum



Direct Microscopic Examination

Septate hyaline hyphae

Arthroconidia




KOH Preparation

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KOH Preparation


Common Clinical Presentations

Tinea pedis: infection of the feet

Primarily involving the soles and toe webs, seenin areas between the third and fifth toes




Tinea Pedis

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Severe Tinea Pedis


Common Clinical Presentation

Tinea cruris: infection of the groin

Including the perineum and perianal region




Tinea Cruris

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Tinea corporis: infection of the smooth skinof the trunk and extremities

Exclusive of the face, foot, groin, hands, or scalp area




Tinea Corporis



Tinea capitis: infection of the scalp,eyebrows, and eyelashes


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Tinea Capitis

Superficial Fungal Infections: Dermatophytes Part 12012 Mayo Foundationfor Medical Educationand Research. All rights reserved.

Onychomycosis:nails and surroundingtissues may be infected by a number of fungiincluding Aspergillus, Fusarium, and others




Onychomycosis

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Microbiology

Tinea pedis

Trichophyton rubrum



Tinea cruris


Trichophyton rubrum




Microbiology

Tinea corporis

Trichophyton rubrum


Microsporum canis

Tinea capitis

Trichophyton tonsurans

Microsporum canis

Microsporum audouini

Trichophyton violaceum




Microscopic IdentificationFrom Mycosel or Cornmeal Agars

Large, smooth-walled, club-

shaped conidia arranged singlyor in clusters of 2 or 3

Colony khaki colored with white areas



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Microscopic Morphologic Features


Hyphae are hyaline, septate, and contain

numerous chlamydoconidia

Macroconidia are blunt, club-shaped,smooth-walled, multicelled

Attached singly or in groups of 2 or 3








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Cultural Features


Colonies are pale olive-green or khaki; some may

be white in color; most are folded and velvety

White sterile hyphae cover the colonies after2 to 3 weeks of incubation






For more information

Visit MayoMedicalLaboratories.comor call Mayo Laboratory Inquiry at 800-533-1710

Questions or requestsE-mail to: [email protected]

2012 07 Derm Pt1 Handout

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