Mycology - all about fungi
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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……..