Test 3: Mycology Flashcards
What is main fungus in oral pathology?
Canadis albicans
What is mycology?
study of fungi
(fungus includes yeast and molds)
What type of environment do eukaryotic fungi require?
aerobic environment
- plant-like but not plants
What does saprophytic mean?
- acquire nutrition from dead, decaying organic matter and that’s what fungi does!
- important in humans because fungi can break down epithelial tissue and spread in immunocompromised pts and tissues that are ischemic and necrotic
T/F: ~150,000 fungal species, but only ~100 are capable of causing infections in humans
True!
What are the 3 things fungi are diverse in?
- appearance (mold on bread)
- benefit/use (wine, cheese, yeast)
- ability to cause disease (pathogenesis/opportunistic)
What are the clinically important morphology forms?
- yeast
- molds
- dimorphic fungi (can display both yeast and molds)
What is yeast morphology?
- single-celled
- round or oval shaped
- reproduce via budding (unequal asexual outgrowth from parent cell; produced genetically identical cells)
If the process in elongation/budding and yeast cells remain attached, what do we call that?
pseudohyphae
What are the examples of yeast morphology?
- candida
- cryptococcus
What is mold morphology?
- multicellular
- filamentous form (if individual filament= hyphae. masses/branching= mycelium)
In the branching of mold, what else do we need to consider?
- they can have septations/cross walls or no separations/no cross walls
(cross walls= septet hyphae MORE COMMON. no cross walls= aseptate/non-septate hyphae MUCOR GROUP)
T/F: Spores can be present in molds
True!
- in pathogenic molds
How dimorphic fungi decide what structure they want?
- based on environmental conditions. USUALLY thermal/temp changes like yeast in the heat, mold in the cold
What are some examples of dimorphic fungi?
- candida (tricky)
- histoplasma
What are the differences in fungus cell structures and why is this important?
- differences in cell wall, cell membrane, chemical components
- important targets for anti-fungal medications
What makes fungal cells different from other eukaryotic cells in regards to cell membrane?
- fungal cell membrane contains ergosterol while human cell membrane contains cholesterol
(ergosterol is an important antifungal target)
What makes fungal cells different from other eukaryotic cells in regards to cell wall?
- no peptidogylcan in fungal cells
(only in bacteria)
What is found in fungal cell wall structures?
- B-glucan
- a-glucan
- chitin (not in human cells)
- mannoproteins
REMEMBER NOT PEPTIDOGLYCAN IN FUNGI
What is found in fungal cell wall structures?
- B-glucan
- a-glucan
- chitin (not in human cells)
- mannoproteins
REMEMBER NOT PEPTIDOGLYCAN IN FUNGI
What do we need to know about fungi metabolism?
aerobic metabolism
What is the asexual reproduction result in, in yeast?
formation of buds
What is the asexual reproduction result in, in mold?
formation of spores
What do we need to know about mold spores?
- molds form spores
- single-cell, small spores= microconidia
- multi-cell, larger spores= macroconidia
- can see both single and multi
What are fungal infections called?
mycoses
When do we see serious disease from fungi infection/mycoses?
- immunocompromised individuals
Where are superficial fungi infections located?
- outermost layers of skin, hair, and nails
What are subcutaneous/submucosal infections caused by usually?
- trauma related inoculation of fungal spores like a prick from a thorn
What are endemic systemic infections?
- cause infection in immunocompetent individual
What are opportunistic systemic infections?
- cause infection in immunocompromised individual
Why do systemic infections occur?
- can be due to commensal fungi that overgrows like candida or due to environmental fungi that is inhaled like mucor
What are pathogenic amoebas we are concerned about?
- entamoeba histolytica
- naegleria fowleri
What are the distinctive features of entamoeba histolytica?
- only one human host in their lifetime
- pseudopods/feet
How many forms are there in amoebas?
only 2 forms:
- adult: trophozoite (feeding stage)
- environmental durable and infectious cyst
What is the transmission of entamoeba histolytica?
- via ingestion of cysts from food or water via fecal-oral route
- only in humans and some primates
- cyst is quite durable in moist environment and can contain chitin
- resistant to chlorine
What is the epidemiology of entamoeba histolytica?
- human waste
- transmission with families and day care settings
What is the dx for entamoeba histolytica?
- repeated 3x microscopic exam of warm feces aka Omar test
- serological testing
- best method: enzyme ELISA for entamoeba histolytica antigens in stool
What is the tx for entamoeba histolytica?
- 2 antibiotic combo: metronidazole and iron chelator iodoquinol
What is the prevention for entamoeba histolytica?
- no vaccines
- improve sanitation (plumbing) and hygiene
What is the prevention for entamoeba histolytica?
- no vaccines
- improve sanitation (plumbing) and hygiene
- be careful when swimming
What is the brain eating amoeba we are concerned about?
naegleria fowleri
(pathogenic= amebic meningoencephalitis)
How does naegleria fowleri carry out its lifestyle?
- carries out its entire life cycle in warm waters
- human are most likely an accidental or dead-end host (why it’s so dangerous)
How do infections occur with naegleria fowleri?
when adult forms invade nasal epithelium
- invasive and can rapidly migrate to the brain with tissue destruction
What are the symptoms of naegleria fowleri infection?
- sudden headache, stiff neck, fever, vomiting, and often altered taste and other perceptions
What is the tx for naegleria fowleri?
- some success with amphotericin B, rifampicin, miconozole
- now: miltefosine (profounda) with induced coma has saved 3 people
