Fungi I Flashcards
what are fungi
*EUKARYOTIC organisms with nucleus, nuclear membrane, endoplasmic reticulum, and mitochondria
how do fungi differ from bacteria and animals
*very different from bacteria (lots of organelles)
*rigid cell wall (unlike humans)
mycoses
fungal infections
superficial fungal infections
*dermatomycoses / tineas
*infections that involve the skin or mucosa
*often due to fungi with low potential for invasion
invasive fungal infections
*deep fungal infections / deep mycoses
*infections that involve internal organs
filamentous fungi
*MOLDS
*grow as MULTINUCLEATE, BRANCHING HYPAE, forming a mycelium
*usually undergo asexual reproduction
*MULTICELLULAR
yeast
*grow as ovoid or spherical SNIGLE cells (UNICELLULAR)
*multiply by budding and division
dimorphic fungi
*form HYPHAE at environmental temperatures
*grow as YEAST in HUMAN host
what are the dimorphic fungi
- blastomyces
- coccidioides
- histoplasma
- paracoccidioides
- sporothrix
superficial fungal infections - overview
*very common
*target skin, hair, nails
*most often caused by dermatophytes
*dx based on clinical features / skin scrapings with KOH
examples of superficial fungal infections
-tinea corporis (ringworm)
-tinea pedis (athlete’s foot)
-tinea cruris (jock itch)
invasive fungal infections (IFIs) - epidemiology
*some are acquired from environment (exogenous in origin)
*some are part of normal human flora (endogenous in origin)
*involve deep organs and/or bloodstream
*may be fatal
*human to human transmission is uncommon
endemic mycoses are aka
dimorphic fungi
*normally found in the environment
what are the best ways to differentiate between the dimorphic fungi
- geography
- appearance on stain
blastomycosis - causative agent
B dermatitidis
blastomycosis - geographic distribution
southeastern/south central US
blastomycosis - acquisition
*INHALATION
*common in outdoor activities near decaying vegetation, moist soil, or body of water
*ex = chopping fire wood, clearing beaver dams
blastomycosis - clinical features
*systemic pyrogranulomatous infection
*majority are SYMPTOMATIC
*causes acute or chronic pneumonia
*may disseminate to SKIN, BONE, and GU TRACT (PROSTATE)
blastomycosis - diagnosis
*BROAD BUDDING YEAST on fungal smears
*confirm with culture
*also, urine and serum antigen detection
histoplasmosis - causative agent
histoplama capsulatum
histoplasmosis - geographic distribution
*ohio and mississippi river valleys
histoplasmosis - acquisition
*INHALATION
*commonly associated with birds/bat droppings, and caves (spelunking)
histoplasmosis - clinical features
*majority ASYMPTOMATIC
*pneumonia if symptomatic
*can disseminate (mouth, bone marrow, spleen)
histoplasmosis - diagnosis
*HISTO HIDES - often found in macrophages or neutrophils
*small, NARROW BASED BUDDING on fungal stain
*confirm with culture
*also, urine and serum antigen tests
coccidioidomycosis - causative agent
coccidioides immitis
coccidioidomycosis - geographic distribution
southWESTERN US
coccidioidomycosis - acquisition
*INHALATION
*commonly seen in disrupted soil/dirt (earthquakes, dust storms, archaeological digs)
coccidioidomycosis - clinical features
~50/50 asymptomatic/symptomatic
*acute or chronic pneumonia
*ERYTHEMA NODOSUM (tender red bumps on shins)
*dissemination to skin, bones and joints, CNS
coccidioidomycosis - diagnosis
*endospores with SPHERULES on fungal smears
*confirm with culture
*also, SEROLOGY
sporotrichosis - diagnosis
*cigar-shaped yeast on fungal stain
*culture
sporotrichosis - acquisition
*INOCULATION (landscapers, gardeners, etc)
sporotrichosis - clinical features
*usually skin and soft tissue disease
*pyrogranulomatous tissue reaction
paracoccidioidomycosis - geographic distribution
central and south america
paracoccidioidomycosis - diagnosis
*PILOT WHEELS on fungal smear
