File - Medical Mycology

advertisement

Superficial, Cutaneous and

Subcutaneous Fungal Infections

Jarrod Fortwendel, PhD

Department of Microbiology and Immunology [email protected]

MSB 2142

Nov. 18-22, 2013

Tinea Capitis in an Adult Woman

87 yo woman presents to her doctor with a 2-year history of puritic, painful, scaling scalp eruption and hair loss

Previous treatment included numerous courses of systemic antibiotics and prednisone without success

Social history: recently acquired several stray cats that she kept inside her home

Physical exam: numerous pustules throughout the scalp, diffuse erythema, crusting, and scale extending to neck.

Extremely sparse scalp hair and prominent posterior lymphadenopathy. No nail pitting.

Wood light positive

Presumptive diagnosis: Tinea Capitis

Cutaneous (and Superficial) Mycoses

Infections of the skin, hair, nail

Invades keratinized layers

Tinea – latin for “worm”

Subgroups of infections

1. Dermatophytoses – “classical ringworm”

2. Non-dermatophytic cutaneous mycoses…

“the other superficial group”

The Dermatophytes –

Classical ringworm - #1 mould infection

Epidemiology

Anthropophilic, zoophilic, geophilic

Transmissible

Invade skin, hair and nails

Collectively called “tinea”

3 major Genera:

Trichophyton

Epidermophyton

Microsporum

The Dermatophytes –

Classical ringworm - #1 mould infection

Epidemiology

Anthropophilic, zoophilic, geophilic

Transmissible

Invade skin, hair and nails

Collectively called “tinea”

3 major Genera:

Trichophyton

Epidermophyton

Microsporum

T. rubrum

T. mentagrophytes

Cause 80-90% of cases worldwide

The Dermatophytes: Pathogenesis

Virulence factors and pathogenesis:

Infectious element

Arthroconidia

Keratin utilization

Keratinophilic and keratinolytic

Hair invasion/colonization

Endothrix, Ectothrix, Favic

Clinical: Classified by anatomical site affected

Tinea capitis

Microsporum spp. –

M. audouinii,

gray patch ringworm

M. canis, M. gypseum

Tinea corporis – point lesion

centrifugal spread –

anywhere on body from eyebrow and neck “southward”

Trichophyton spp., Epidermophyton, (Also Candida)

Tinea pedis

cosmopolitan

Trichophyton spp., Epidermophyton

Tinea unguium

Often as a secondary infected site

Almost any dermatophyte, esp Trichophyton rubrum, (Also Candida)

Tinea capitis

Tinea corporis

Tinea imbricata

Etiology: Trichophyton concentricum

Tinea cruris

Tinea cruris

Tinea unguium - onychomycosis

Tinea barbae

Tinea manum

Dermatology Image Atlas: Dermatology Images - dermatlas.med.jhmi.edu

Tinea pedis

The Dermatophytes - Zoophilic

The Dermatophytes - Zoophilic

Laboratory Diagnosis

Requires demonstrating hyphae/arthroconidia from skin, hair, nails

Direct preparation:

Lesion scrapings/hair examined by calcofluor/KOH

Alternatively - Wood’s Light:

UV irradiation of infected hair, false positive/negative

Report: Hyphal fragments/arthrocondida seen

Culture: SDA +; SDA-CC +

LPCB

Direct KOH prep: Hyphal fragments seen http://www.mycology.adelaide.edu.au/virtual/2009/ID2-Oct09.html

The Dermatophytes:

Morphology

Epidermophyton spp.

- Smooth walled macroconidia borne in clusters of 2 or 3; no microconidia

Trichophyton spp.

- Rare, smooth, thin-walled macroconidia; numerous spherical or teardrop shaped microconidia

Microsporum spp.

- Numerous, large, thick, rough-walled macroconidia; rare microconidia

Treatment of the dermatophytoses

Localized cutaneous - topical agents

Clotrimazole (Lotrimim), Miconazole (micatin)

Tolnaftate (tinactin), terbinafine (lamisil)

Hair, nails – oral therapy

Fluconazole, itraconazole, griseofulvin

Griseofulvin

Concentrates in newly keratinized layers of cells

Virtually eradicated epidemic tinea capitis; used in tinea unguium and extensive infections.

Recurrences are common

Non-dermatophytic Onychomycosis:

Candida spp.

Fluconazole

Scopulariopsis spp.

Scytalidium spp.

partial surgical nail removal + antifungal

**Possible other nail pathogens:

Aspergillus spp.

Fusarium spp.

Acremonium spp.

**

nail pathogen vs. saprobe on abnormal nail material **

Must have: > 1 KOH positive!!

> culture positive isolation of same agent!!

**R/O fungal contamination of the culture**

Case resolution…

Wood Light – positive

Skin biopsy

Enterococcus spp. and Trichophyton tonsurans

Endothrix dermatophyte infection

Treated with griseofulvin and Selsun

New hair growth and resolution of pustular eruption at 2 week follow-up

Treatment continued for 8 weeks with complete hair re-growth and no permanent alopecia

Superficial Mycoses

Tinea versicolor – AKA pityriasis versicolor

Malessezia furfur

Tinea nigra palmaris

Hortaea (Exophiala) werneckii

Piedra – black

Piedraia hortai

Piedra – white

Trichosporon beigelii

Superficial Mycoses

Tinea versicolor – AKA pityriasis versicolor

Malessezia furfur

Very common – up to 60% infected population in certain tropical environments

Most common in tropic and subtropics

Person-to-person transfer

Liopophilic fungus that degrades lipids to produce acids that damage melanocytes = hypopigmented patches w/ dark skin, pink or brown w/ light skin

Little-to-no host immune reaction

Tinea (pityriasis) versicolor

Chest

Back

Skin Scraping – Direct Prep (KOH)

“Spaghetti and meatballs”

Diagnosis made by direct exam

Does not culture routinely - lipophilic

Treatment: 2.5 % Selenium sulfide or topical cream azoles

Severe cases: Oral ketoconazole

“collarette”

Superficial Mycoses

Tinea versicolor – AKA pityriasis versicolor

Malessezia furfur

Tinea nigra

Hortaea (Exophiala) werneckii

Piedra – black

Piedraia hortai

Piedra – white

Trichosporon beigelii

Superficial Mycoses

Tinea versicolor – AKA pityriasis versicolor

Malessezia furfur

Tinea nigra

Hortaea (Exophiala) werneckii

Superficial phaeohyphomycosis

Solitary, irregular, pigmented macule usually on palms or soles

Tropic or subtropic

Traumatic inoculation

Not contagious

Can resemble a malignant melanoma

Tinea nigra – H. werneckii

2. Culture = dematiaceous, yeast-like colony in 3 weeks

4. Treatment:

Topical azoles

1. KOH prep = pigmented hyphae and yeast http://www.mycology.adelaide.edu.au/virtual/2007/ID2-Feb07.html

3. Microscopic

= two-celled, cylindrical, yeast-like cells http://www.mycology.adelaide.edu.au/virtual/2007/ID2-Feb07.html

Superficial Mycoses

Tinea versicolor – AKA pityriasis versicolor

Malessezia furfur

Tinea nigra palmaris

Hortaea (Exophiala) werneckii

Piedra – black

Piedraia hortae

Piedra – white

Trichosporon beigelii

Superficial Mycoses

Tinea versicolor – AKA pityriasis versicolor

Malessezia furfur

Tinea nigra palmaris

Hortaea (Exophiala) werneckii

Piedra – black

Piedraia hortae

Tropical, poor hygiene, uncommon

Small, dark nodules surrounding hair shaft

Clumped together by cement-like substance with asci and ascospores

Diagnosis = direct exam

Treatment = haircut, washing

Superficial Mycoses

Tinea versicolor – AKA pityriasis versicolor

Malessezia furfur

Tinea nigra palmaris

Hortaea (Exophiala) werneckii

Piedra – black

Piedraia hortai

Piedra – white

Trichosporon beigelii

Tropical and subtropical, poor hygiene

Affects hairs of groin and axillae

Forms soft, white/brown swelling on hair shaft

Shaving and washing

Superficial Mycoses

Tinea versicolor – AKA pityriasis versicolor

Malessezia furfur

Tinea nigra palmaris

Hortaea (Exophiala) werneckii

Piedra – black

Piedraia hortai

Piedra – white

Trichosporon beigelii

Other non-dermatophytic (several)

E.g. Candida, Fusarium, and more…

Subcutaneous mycoses

AKA: Inoculation Mycoses – normal soil inhabitants

Primary infection in deep skin, muscle or connective tissue

Slowly progressive and chronic, usually confined

Not transmissible

Subgroups of subcutaneous mycoses

I.

Sporotrichosis

II.

III.

IV.

Chromoblastomycosis/Phaeohyphomycosis

Mycetoma

Subcutaneous Zygomycosis

Sporotrichosis – Sporothrix schenkii

Epidemiology :

Decaying vegetation, esp used for mulching

Enters via splinters, thorn pricks

-Occupational hazard

Clinical Aspects:

Primary nodular lesion

 necrotic ulcer, suppurative

Proximal lymphatics may chronically infect (dissemination rare)

Sporothrix schenckii:

Direct prep: RARE blastoconidia

Sporothrix is a thermal dimorph

At RT: DEMATIACEOUS colony, HYALINE septate hyphae, delicate lateral conidiophores w/ delicate rosettes of conidia

At 37°C in vivo & in vitro: oval, cigar-shaped blastoconidia.

Treatment:

Itraconazole

Chromoblastomycosis

Epidemiology:

– tropics – PR, Cuba, Costa Rica and Brazil

Soil saprobes; dematiaceous fungi

Trauma is required, occurs when shoes are rarely worn

Clinical Manifestations:

Not contagious

Incubation unknown

Chronic skin and subcutaneous infections

Small raised papule, ulcerates & encrusts

 dry, raised lesion usually on foot/leg

Satellite lesions hyper-elevate - 10-15 yrs from onset

Chromoblastomycosis –

Clinical Manifestations

Chromoblastomycosis

Laboratory Diagnosis:

Direct Prep: Copper-colored, multiple dividing cells

Three major organisms: Cladosporium, Fonsecaea, Phialophora

Culture = differ by conidial structures

Can be considered dimorphs – yeast-like in vivo, mould in vitro

Treatment:

Specific antifungals usually ineffective

Itraconazole, terbinafine, or posaconazole

Combined with 5-fluorocytosine in refractory cases

Phaeohyphomycosis

Epidemiology:

Syndrome caused by more than 20 different saprobes

Fungi appear in tissue as irregular hyphae, not the sclerotic cells seen in Chromoblastomycosis

Traumatic inoculation

Clinical syndromes:

Solitary inflammatory cyst

Slow growing (months to years)

Laboratory Diagnosis:

Surgical excision of cyst = inflammatory cyst with fibrous capsule, necrosis, fungal elements

Treatment:

Surgical excision

Itraconazole, posaconazole, voriconazole, terbinafine

Mycetoma

Epidemiology :

– tropical & subtropical

Soil saprobes

Trauma required for inoculation

Clinical Manifestations:

Not contagious

Swollen deep seated lesion of hand or foot

Mycetoma – Clinical Manifestation

Mycetoma

Laboratory diagnosis:

Caused by many diverse microbes

Eumycetoma (fungal mycetoma)

Scedosporium (teleomorph Pseudallescheria)

Resistant to Amphotericin B!

Actinomycetoma (actinomycotic mycetoma)

Actinomyces, Nocardia, Actinomadura, Streptomyces

Treatment:

Bacterial – antibiotics

Fungal – surgery and long-term treatment

Subcutaneous Zygomycosis

Epidemiology:

Africa, India, Latin America

Traumatic implanation

Conidiobolus coronatus and Basidiobolus ranarum

Clinical Syndromes:

B. ranarum – large, movable mass localized to shoulder, pelvis, hip and thigh

C. coronatus – confined to rhinofacial area

Laboratory diagnosis:

Biopsy = focal clusters of inflammation, eosinophils, zygomycete hyphae

Treatment:

Itraconazole

Download