CLINICAL MYCOLOGY 2

INNOCENT AFEKEUHAS

SUPERFICAL /CUTANEOUS MYCOSES

(DERMATOPHYTES)

Infections strictly confined to keratinized epidermis (skin, hair, nails) are called

dermatophytoses e.g. ringworm , tinea and athlete’s foot

Source of infection:

• Anthropophilic: Associated with humans only. Person -to-person transmission through contaminated objects (comb, hat, hospital beddings etc.)

• Zoophilic: Associated with animals. Direct transmission to humans by close contact with animals (pets)

• Geophilic : Usually found in soil. Transmitted to humans by direct exposure (occupational hazards: gardeners & farmers)

• Have 3 Genera of Dermatophytes of clinical importance (MET)

• Microsporum

• Epidermophyton

• Trichophyton

(MET)

Microsporum

• 13 species are known• Affects Hair and Skin• Culture shows cottony aerial hyphae• Microscopy :thick wall, spindle shape,

multicellular• Microsporum canis:

• Lab. Culture and Microscopy

Epidermophyton floccosum• Affects Nails and Skin• Culture: cottony , range of colours• Microscopy: Bifurcated hyphae with multiple,

smooth, club shaped macroconidia (2-4 cells)

• Lab culture and Microscopy

Trichophyton

• 19 species are known• Affects Hair, Skin and Nails

• Lab Culture and Microscopy

Superficial mycoses

Pityriasis versicolor – pigmented lesion on torso (trunk).

- Tinea nigra – gray to black macular lesion

on palms.

- Black piedra – dark gritty deposits on hair.

- White piedra – soft whitish granules along

hair shaft.

Tinea infections: Red, scaly or blister-like lesions; often a raised red ring; “ringworm

• Tinea pedis

• Tinea corporis

• Tinea capitis

• Tinea favosa

• Tinea barbae

• Tinea cruris

• Tinea unguium

Samples for Lab Investigation

• Skin scrapings for culture

&microscopy

• Cutting of part of nail

• Shave hair (at the edge not middle)

• Comb culture

• Zig-lock bag (envelop) ; send to lab • Culture of comb

THERAPY FOR DERMATOPHYTES

• Clotrimazole

• Miconazole

• Ketoconazole

• Itraconazole

• Griseofulvin

• Tinactin

• Terbinafine

Subcutaneous Mycoses

• Infections beneath the skin; Hyphae or spores in wounds

• More serious than cutaneous mycoses

-Sporothrix schenkii

-Soil organism

-mode of transmission is by inoculation through abrasive skin

• Gardeners=ulcers on hands or foot

• Chronic infection

• May accompany with secondary infection

• Treatment is slow

Subcutaneous Mycosis: MYCETOMA

-It is a chronic infection of the skin, subcutaneous tissue and sometimes bone

- Mycetoma may be due to several fungi or actinomycetes (actinomycetoma• Actinomycetes are bacteria producing

filaments like fungi

- The organism is inoculated into the skin by a minor injury, for example, a cut with a thorn when barefoot

CANDIDIASIS

• Mucosal normal microbiota suppresses the growth of Candida albicans

• Vaginitis and thrush are initiated by:-Antibiotics eliminate normal microbiota-pH changes

• Infants who may not have their normal microbiota established=thrush

• Thrush & Vaginal Candidiasis

SYSTEMIC OR DISSEMINATED MYCOSES

Systemic Candidiasis• Hematogenous dissemination from a

localized infection

• Spreads to organs like-Kidney-Spleen-Lung-Liver• Fungal Blood Culture may be positive

• Culture of surgical tissue sample may be positive (invasive procedure)

• Liver infected with Candida/Culture on medium

Systemic Mycoses Disseminated from Respiratory System

(1)HISTOPLASMOSIS (Histoplasma capsulatum)• Resembles tuberculosis• Vague symptoms• Transmission

-Airborne conidia-Bats: Carry fungus in feces -Birds: Feces

• May affect all organs• Dimorphic fungi• Yeast lives within macrophages and multiplies• In USA , cases mainly from Mississippi river and Ohio river states

• DiagnosticBlood test—Antibody titre X-ray

• Treatment (intravenous)-Amphotericin B-Itraconazole

(2) COCCIDIOIDOMYCOSIS• Two species: Coccidioides immitis & Coccidioides posadasii

• Arthrospores in dry alkaline soils (found in specific geographic areas)

• Transmitted by wind

• Dimorphic fungi

• Disease called Valley Fever

• Symptoms-Chest pain-Fever-Cough-Extreme fatigue

People at risk• Immunosuppressed Patients– -organ transplant -lymphoma -HIV+/AIDS -adrenal corticosteroid therapy-diabetes -3rd trimester pregnancy

• In normal individuals;-Most infections are asymptomatic-Most recover in a few weeks

Diagnostic- Identification of spherules in tissues

C. Immitis spherule in lung tissue

Macroscopy &Microscopy diagnosis of C. immitis in Brain tissue

(3) BLASTOMYCOSIS : Blastomyces dermatitidis• Spores found in soil in Mississippi Valley (geographically specific)• The main route of infection is by inhalation of spores• Dimorphic fungus• Most infections are asymptomatic• Begins at lungs and spreads• The disease may disseminate into the skin, bones, or urogenital tract• Major symptoms in humans include loss of weight, fever, cough, and bloody

sputum and chest pains. • Diagnostic

-Isolation of organism from pus and biopsies

• Treatment-Amphotericin B

Opportunistic Mycosis

(1) PNEUMOCYSTIS PNEUMONIA : Pneumocystis carinii• Leading cause of death in AIDS patients• Present in healthy lungs (Normal flora)• 1993-Indicator of AIDS

(2) Other respiratory opportunistic fungi• Aspergillus fumigatus• Aspergillus spp.-present in decaying vegetation• Rhizopus spp.• Mucor spp.

(3) Cryptococcosis: Cryptococcus Neoformans• Causes Yeast Meningitis in humans• Cryptococcosis in humans usually begins as a primary infection of the lungs. • Most of the cryptococcal infections occur from inhalation of the fungi along

with the dust from areas enriched with pigeons manure• There are no visible early symptoms may include cough, chest pain, weight

loss, fever or dizziness. • The disease may be in the lungs, mucous membranes, bones, and joints, with

no organ or tissue of the body exempt.

• Lab Diagnosis:-Identification of yeast in CSF and othertissue fluids-Culture and biochemical test

FUNGAL DISEASES OF THE DIGESTIVE SYSTEM

•Mycotoxins: Fungal Toxins(a) Ergot poisoning• Claviceps purpurea• Infects Grain Crops• Ergotism: Disease caused by ingestion of contaminated grains• Causes hallucination• The chemical responsible for the hallucinations is actually LSD! lysergic acid• Another ergot derivative may cause spontaneous abortions

• The history of ergot in small town “The day of St Anthony's Fire"

(b) Aflatoxin poisoning• Aflatoxin is a naturally occurring mycotoxin produced by two types of mold

Aspergillus flavus and Aspergillus parasiticus• Peanuts and cottonseeds• Acute intoxication

-Liver damage

• Chronic intoxication-Liver cancer-Depending on the levels, the toxins can severely affect the liver and they are a known human carcinogen