MYCOLOGY

Dr. Ashish V. JawarkarM.D.

Warning!!!!!!

Mycology

Greek – mukes – fungus Candida was described early as 1839 But fungi were not studied till recently

because most infections are mild After bacterial infection control

developed, fungal infections became more common

Fungi cause serious infections in immunosupressed and those on steroid treatment

BASICS

Fungi are eukaryotes Have multilayered cell wall Bilayered cell membrane

Types

Depending on cell morphology Yeasts Molds Dimorphic

Yeast

Unicellular, reproduce by budding

Examples of yeasts

Candida Cryptococcus neoformans malassezia

Molds

Examples of molds

dermatophytes

Classification according to type of infection Superficial infections Subcutaneous infections Systemic infections

Superficial mycoses

Affect skin, hair, nails and mucous membranes

Include Candidosis Pityriasis versicolor Tinea Pedra dermatophytosis

Candidosis

Usually superficial – infect skin, nails and mucous membranes

Systemic infection in immunosupressed

Yeast and hyphae – dimorphic fungus

Lab diagnosis

Wet films Gram stain – budding gram positive

cells Sabourand’s dextrose agar

Pityriasis versicolor

Areas of depigmentation or hyperpigmentation on skin of trunk, abdomen and upper limbs

Diagnosis by skin scrapings – yeasts seen

Tinea nigra

Infection of palms Black or brownish lesions Hyphae and budding yeasts on smear Cultured on SDA, green to black

colonies

Piedra

Infection of hair Irregular nodules on hair shaft

Dermatophytosis

Skin, hair and nails a/k/a tinea or ring worm About 40 of them are known Classified on the basis of type of

colony on SDA and spores they produce

spores

Classification

Trichophyton – only micro microsporum – both micro and macro Epidermophyton – only macro

Colonies Trichophyton – powdery Microsporum – cotton like – with

pigmentation Epidermophyton – greenish yellow

color

Ringworm

Epidemiology

Classified into three types accd to source Anthrophilic – human beings eg tinea

rubrum Zoophilic – animals – M canis Geophilic - soil

Lab diagnosis

KOH mount

ectothrix

endothrix

Lab diagnosis

SDA

trichophyton

epidermophyton

microsporum

SUBCUTANEOUS MYCOSES

Mycetoma

Infection of subcutaneous tissue of foot

Reported from Madurai – a/k/a madura foot

Multiple sinuses are seen in foot discharging pus onto surface

Pus contains ‘sulfur granules’ which are colonies of fungi

Chromoblastomycosis

Cauliflower like lesions on lower limb Fungi are in soil, enter at site of

trauma Seen in bare foot agricultural workers

Diagnosis by demostration of sclerotic bodies on histology or KOH mount

SPOROTRICHOSIS

Fungus found on thorns Infection seen in gardeners Nodules are seen in skin, along

lymphatics and lymphnodes Upper limb Caused by fungus Sporothrix

schenckii

Diagnosis by demostration of asteroid bodies

RHINOSPOROIDOSIS

Polyps around nose, mouth or eye Majority cases from Sri lanka Agent Rhinosporoidium Seeberi

SYSTEMIC MYCOSES

Systemic mycoses

Affect multiple body systems, usually spread through blood stream

Two groups True pathogens – cause disease in healthy

• Histoplasma• Blastomyces• P. marneffei

Oppurtunistic pathogens – cause disease in immunosupressed

• Candida• Aspergillus• Zygomycetes

Other • Cryptococcus neoformans

CRYPTOCOCCUS NEOFORMANS Yeast Found in feces of pigeons/birds Most often seen in patients with HIV

Fungus is inhaled Can cause pneumonia, meningitis,

skin ulcers etc. Diagnosis by demonstration of

capsulated budding yeast in CSF/sample

India ink is used to demostratecapsule

Negative staining – India ink

Histoplasma

Grows as mold in nature, yeast in tissues

Most common in USA In India found in west bengal Found in bird feces Inhaled – lung infection, may spread

Oppurtunistic systemic mycoses

Candidosis

Common in immunosupressed Can affect kidneys, liver, spleen Diagnosis by blood culture, tissue

biopsies

Aspergillosis

Enough of negativity……..