Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
89 Cards in this Set
- Front
- Back
|
how many species of fungi are there?
|
250,000
|
|
|
how many species of fungi cause disease?
|
180
|
|
|
what type of organisms are fungi?
|
eukaryotes, membrane bound
|
|
|
what type of genome do they have?
|
haploid with introns (around 6000 genes) in nucleus
|
|
|
what does the membrane contain?
|
ergosterols, mannose containing glycoproteins
|
|
|
what is the cell wall composed of?
|
glycan (glucose and mannan), B1,4-linked-N-acetylglucosamine residues, B1,3-linked glucose, glycoproteins
|
|
|
what may be linked to the glycoproteins?
|
asparagine N-linked mannose/galactose, serine/threonine O-linked mannose/galactose residues
|
|
|
what are dimorphic fungi?
|
can exist in either filamentous or yeast
|
|
|
when are dimorphic fungi filamentous?
|
environment under 22C
|
|
|
when are dimorphic fungi yeasts?
|
body over 37C
|
|
|
what is pseudohyphate?
|
short cyclinders by which yeast grows
|
|
|
how do yeasts mutliply?
|
mitosis: symetrical binary fission or asymetrical budding
|
|
|
what are hypha?
|
thin branching multicellular cylinders (filamentous mould),
|
|
|
how do filamentous moulds mutliple?
|
mitosis at tip or branch point
|
|
|
how are cells held together in a hypha?
|
interconnecting cytoplasm or aseptate (common cytoplasm with many nuclei)
|
|
|
what is a mycelium?
|
interwoven mass of hyphae
|
|
|
what are mushrooms?
|
many layers of mycelium
|
|
|
what are spores?
|
small, tough, light fungal cells, adapted for survival in hostile habitats
|
|
|
what is the asexual state?
|
asexual spores produced by mitosis
|
|
|
what are other names for the asexual state?
|
anamorph/mitotic/imperfect state
|
|
|
what type of spores do yeast in asexual state produce?
|
endospores (internal)
|
|
|
what type of spores do filamentous moulds in asexual state produce?
|
exteranal conidia or internal sporagium
|
|
|
what species can only exist in the asexual state?
|
deuteromycota (imperfect fungi)
|
|
|
what are the other names for the sexual state?
|
telpomorph/meiotic/perfect state
|
|
|
what structures are produced in the sexual state?
|
motile gametes or sexual hyphae
|
|
|
how does sexual reproduction occur?
|
gametes/hyphae fuse, reassortment and recombination occur, meiotic reduction division allows two haploid cells to form
|
|
|
where do sexual spores form?
|
ascus (internal tube), abasidium (external structure) or fusion of hyphae
|
|
|
what are examples of ascomycota species?
|
candida (yeast) microsporum (mould) histoplasma (dimorphic)
|
|
|
what are examples of basidiomycota species?
|
cryptoccus (yeast)
|
|
|
what are examples of zygomycota species?
|
mucor (mould)
|
|
|
what are examples of deuteromycota species?
|
coccidioides (dimorphic)
|
|
|
what reproductive structures do ascomycota make?
|
ascus (sexual), conidia (asexual)
|
|
|
what reproductive structures do basidiomycota make?
|
abasidium (sexual),
|
|
|
what reproductive structures do zygomycota make?
|
fusion from hyphae (sexual), sporangium (asexual)
|
|
|
what reproductive structures do deuteromycota make?
|
conidia (asexual)
|
|
|
how do they get their energy
|
preformed organic compounds, extracellular digestion
|
|
|
where do yeasts live?
|
moist environments
|
|
|
where do filamentous moulds live?
|
within their food
|
|
|
what are saprotrophs?
|
feed on dead matter, rarely disease causing
|
|
|
what are the uses of fungi?
|
bread making (CO2), alcohol (ethanol), antibiotics (penecillin), immunosuppressants (cyclosporin)
|
|
|
what is the immune response to fungi?
|
NFKB causes IL6/23/1B -> Th17 (IL17 and 22 to recruit neutrophils) and IL12/TNFa -> Th1 cells (IFNy to activate macrophages)
|
|
|
what disorders result in a lack of B1-3glycan sensing?
|
Dectin-1 deficiency and CARD9 mutations
|
|
|
what increases suceptibility to candida species?
|
IL17 and IL22 autoantibodiess
|
|
|
what increases suceptibility to deep filamentous mould infections?
|
neutropenia (impaired number and function of neutrophils), Chronic granulomatous disease
|
|
|
what is chronic granulomatus disease?
|
mutation in NADPH oxidase system stops the formation of the superoxide that kills fungi in phagosomes
|
|
|
what predisposes to infections by yeast?
|
primary immunodeficiency syndrome (impaired T cell/macrophage function), HIV etc
|
|
|
what drugs can be used to target ergosterol synthesis?
|
azoles (clotrimazole) and allylamines (terbinafine)
|
|
|
what drugs can be used to target ergosterol function?
|
polyenes (amphotericin)
|
|
|
what drugs can be used to target microtubules?
|
griseofulvin
|
|
|
what drugs can be used to target B1,3-glycan synthesis?
|
echinocandins (caspofungin)
|
|
|
what types of fungal infection may you get?
|
food intoxication, commensal infection, superficial, subcutaneous or systemic fungal infections
|
|
|
what fungal food intoxication?
|
rye crops may contain ergotamine toxin causing vasoconstriction
|
|
|
what fungi is a commensal that can cause infections?
|
candida
|
|
|
what is a superficial fungal infection?
|
ring worm, microsporum, candida albicans, pityriasis versicolor
|
|
|
what is infected in superficial infections?
|
dead keratinised skin
|
|
|
how could you treat tinea ungium (nail) or tinea pedis (feet) infections?
|
topical clotrimazole/terbinafine
|
|
|
how are superficial infecitons aquired?
|
spores
|
|
|
what type of infection do you get with superficial infections?
|
chronic, non lifethreatening
|
|
|
what do mannose rich structures cause?
|
activation of complement via MBL
|
|
|
what does TLR2 recognise?
|
phospholipomannan
|
|
|
what does TLR4 recognise?
|
O-linked mannose
|
|
|
what does Dectin 1 recognise?
|
B 1-3 glycan
|
|
|
what signalling does dectin 1 cause?
|
inflammasome and syk/CARD9/MALT1 -> NFkB
|
|
|
how are subcutaneous fungal infections acquired?
|
injury/occupational hazards
|
|
|
what is sporothrix schenckii?
|
rose pickers disease, chronic disease spreads up skin of arm
|
|
|
what type of fungi can cause asymptomatic infection of macrophaes?
|
deep systemic pathogens
|
|
|
what are systemic pathogens?
|
infection is accidental (not needed for life of fungus)
|
|
|
what is histoplasma capsulatum?
|
dimorphic fungus in soil/rat faeces, can live inside macrophages
|
|
|
what causes the dimorphism of histoplasma capsulatum?
|
temperature sensitive DRK1 and RYP1 kinases
|
|
|
how can histoplasma capsulatum avoid the immune system?
|
a-1-3 glycan isn't recognised by PRR, hsp60 binds to CD11 and CD18 on macrophages, CBP (calcium bind protein) faciliates growth in macrophages
|
|
|
what are the types of histoplasma capsulatum infection?
|
asymptomatic (95%), acute pulmonary (flu like), chronic pulmonary (fibrosis), dissemination (spreads - fatal)
|
|
|
what are systemic oppurtunists?
|
severity relates to underlying host infection
|
|
|
what helps some strains of candida albicans have increases adhesion and invasion?
|
pseudohyphae (since yeast in body)
|
|
|
what is the toxin secreted by candida albicans important in virulence?
|
candidalysin (damages epithelial cells)
|
|
|
what other feature of candida albicans makes it problematic?
|
biofilm formation in extracellular matrix
|
|
|
how can you treat candia infections?
|
fluconazole/caspofungin
|
|
|
what are the types of candida infection?
|
oral candidasis, vulvo vaginitis, UTI, oesophagitis, candideamia (IV cannula), disseminated (spread to eyes, liver, heart valves)
|
|
|
what is pneumocystis jirovecii?
|
obligate parasite in humans - lost amino acid sysntheis capacity (yeast)
|
|
|
how many people are infected with pneumocystis jirovecii?
|
almost everyone within 3 years (asymptomatic)
|
|
|
what disease does pneumocystis jirovecii cause in immunosuppressed people who reacquire a strain?
|
lung disease (10% have mutliple strains), pneumocystitis pneumonia
|
|
|
how do you treat pneumocystis pneumonia?
|
high dose co-trimoxazole to inhibit folic acid synthesis and corticosteroids to reduce inflammation
|
|
|
what is cryptococceus neoformans?
|
yeats with thick polysaccharide capsule, abundant in bird droppings
|
|
|
what types of infection can you get from cryptococceus neuformans?
|
pneumonia, meningo-encephalitis (when T-cell suppressed or HIV positive - 20% fatality)
|
|
|
how do you treat meningo-encephalitis?
|
amphotericin and flucytosine and long term fluconazole
|
|
|
what is aspergillus fumigatus?
|
environmental mould with airborn spores, in compost
|
|
|
what types of infection can you get from aspergillus fumigatus?
|
airway colonisation (asthma), aspergilloma (localised mass of hyphae), invasive infection (eg following chemotherapy)
|
|
|
how would you treat aspergillus fumigatus?
|
amphotericin or voriconazole and surgery
|
|
|
what is Mucor?
|
environmental mould with airborn spores, causing fatal mucormycosis
|
|
|
how would you treat mucor?
|
IV amphotericin
|
