ผศ. กญัญลกัษณ์ ชัยค ำภำ

Fungal infection of skin

Superficial mycoses

Pityriasis versicolor

Cutaneous mycoses

Dermatophytoses

Candidiasis

Subcutaneous mycoses

Mycetoma

Objectives

• Etiologic agent of infection

• Sign and symptoms

• Characteristic appearance

• Lab diagnosis

• Prevention and treatment

1. Pityriasis (Tinea) versicolor (เกล้ือน)

chronic, superficial fungal disease of the skin

Fungus Malassezia furfur

at least 20 different Malassezia spp. recognized

currently

M. furfur ***

M. globosa ***

M. sympodialis ***

M. slooffiae

M. restricta

M. obtusa etc.

Hypopigment lesion

Pityriasis or Tinea versicolor (เกลือ้น)

Fungus : normal flora

Factors effect invasive power

-squamous cell turnover rate

-sweaty / oily skin

-extracellular glycogen

-poor hygiene

-corticosteroids / antibiotics

symptoms small macule on chest, back, arm, neck

usually no inflammation, no itch

Most common in adolescent and young adult males

Stratum corneum Hypopigment Hyperpigment

Pityriasis foliculitis

Dandruff (= Pityriasis capitis)

– caused by M. globosa

– accellerated shedding of skin cells

Lab diagnosis

Direct examination

10-20% KOH

budding yeast, short hyphae

Culture

lipophilic yeast (Suppl.: olive oil)

Treatment

mild fungicidal / keratolytic agent

Tissue form / parasitic form

“ spaghetti & meatballs ”

2. Dermatophytoses (กลาก)

Ringworm, Tinea

Dermatophytes or keratinophilic fungi

3 genera

• Trichophyton

• Microsporum

• Epidermophyton

2. Dermatophytoses

Ringworm, Tinea

Dermatophytes or keratinophilic fungi

3 genera

Genus Macroconidia Microconidia

Trichophyton Pencil +++

Microsporum Spindle ++

Epidermophyton Club absent

Dermatophyte Origin Fungi

Geophilic soil M. gypseum

Zoophilic animal M. canisT. mentagrophyte

Anthropophilic human T. rubrumE. floccosum

“active border”

Diseases named by lesion site

Tinea capitis Tinea corporis

Tinea faciei Tinea cruris

Tinea barbae Tinea manuum

Tinea unguium Tinea pedis

Tinea imbricata Tinea favosa

Tinea capitis

Tinea corporis

Tinea faciei

Tinea cruris Tinea barbae

Tinea unguiumTinea manuum

Tinea pedis

Tinea imbricata

Tinea favosa

Lab diagnosis

1. Direct exam. 10% KOH

branching septate hyphae

arthrospore

2. Culture 25oC

SDA= Sabouraud’s dextrose agar

Mycosel= SDA+ chloramphenicol+

cycloheximide

Slide culture

Treatment : Griseofulvin, azoles

Tissue form

Slide culture

3. Candidiasis ( Candidosis )

Fungus: genus Candida -- “yeast-like fungi”

-Yeast

-Blastospore

-True hyphae

-Pseudohyphae

3. Candidiasis ( Candidosis )

Fungus: genus Candida -- “yeast-like fungi”

spp.---- C. albicans (90%), C. tropicalis,

C. glabrata, C. dubliniensis etc.

Source: normal flora, H2O, soil, food

opportunistic infection

Disease caused by Candida spp.

1. Mucocutaneous candidiasis

-oral thrush

-vaginal candidiasis

-candidal balanitis

2. Cutaneous candidiasis

-skin

-nail

( 3. Systemic candidiasis )

Candidiasis

Oral thrush

Paronychia

Onychomycosis

Virulence factors of Candida - Adhesins- Yeast-hypha transition - Hydrolytic enzyme : proteinase, phospholipase etc.- Phenotypic switching

Yeast-hypha transition

germ tube

Phenotypic switching

in

Candida albicans

Switching

White

Opaque

Stages of a Candida infection

adhesion & colonisation

epithelial penetration

vascular dissemination

endothelial colonisation and penetration

Lab diagnosis

1. Direct exam. KOH preparation, Gram’s stain

2. Culture SDA (chloramphenicol) 37oC

Yeast colony

Lab diagnosis

1. Direct exam. KOH preparation

Gram’s stain

2. Culture SDA (chloramphenicol) 37oC

Presumptive test for C. albicansGerm tube formation

plasma 37oC, 2-3 hrs.

Terminal chlamydospore

Corn meal agar + Tween 80

Germ tube

Terminal chlamydospore

Lab diagnosis

1. Direct exam. KOH preparation

Gram’s stain

2. Culture SDA (chloramphenicol) 37oCnon-albicans Candida spp.

Germ tube formation

plasma 37oC, 2-3 hrs.

Terminal chlamydospore

Corn meal agar + Tween 80

Biochemical test

Treatment : Nystatin, Amphotericin B, Azoles

4. Mycetoma

tumefaction

draining sinusgrain or granule

*Actinomycetoma

*Eumycetoma

Dematiaceous

5. Sporotrichosis

“ Rose-picker's disease ”

Sporothrix schenckii dimorphic fungi