Published on March 4, 2014
MYCOLOGY Dr. Ashish V. Jawarkar M.D.
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
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
Classification Trichophyton – only micro microsporum – both micro and macro Epidermophyton – only macro Colonies Trichophyton – powdery Microsporum – cotton like – with pigmentation Epidermophyton – greenish yellow color
Epidemiology Classified into three types accd to source Anthrophilic – human beings eg tinea rubrum Zoophilic – animals – M canis Geophilic - soil
diagnosis ectothrix KOH mount endothrix
Lab diagnosis SDA trichophyton
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 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 demostrate capsule
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
Enough of negativity……..
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