WorksheetsMycology III
Total questions: 27
Worksheet time: 29mins
Victor noticed unusual brown-black discolourations on the palm of his right hand and presented to his local medical centre two weeks later. Victor has no other symptoms. The GP suspects he has a fungal infection and collected a skin scraping to send to diagnostic lab. Victor most likely has which of the following types of fungal infections?
invasive mycosis
superficial mycosis
subcutaneous mycosis
cutaneous mycosis
none of the above
Which of the following fungal species is most likely responsible for superficial mycosis?
Aspergillus fumigatus
Rhizopus spp.
Candida albicans
Crytococcus neoformans
Dermatophytes
Commensal bacteria play an important role in preventing the overgrowth of Candidia albicans. If the commensal bacteria are disturbed or absent, greater numbers of C. albicans can colonise the mucosal epithelium. This is due to:
decreased mucus production by host cells
increased secretion of short-chain fatty acids by epithelial cells
reduction in shear forces
increased expression of candidalysin by C. albicans
reduced competition for adhesion sites on epithelial cells
Which of the following strategies is NOT used by Candida albicans to evade innate immunity?
shielding of PAMPS
inhibition of neutrophil recruitment and neutrophil extracellular traps (NETs)
escape from the phagosom
biofilm formation
resistance to antimicrobial peptides
Which of the following is NOT a challenge encountered by Candida albicans when it enters a new host?
fluid fluxes
biofilm formation
cytokines
reactive oxygen species
pH changes
Which of the following describes the role/s that Als3 protein plays in Candida albicans invasion?
mediates yeast cells' attachment to host cell
promotes the formation of an invasion pocket
allows fungal hypha to bind to E-cadherin
Advantages to the yeast from biofilm formation include:
protection from immune cell action
physical protection by formation of an extracellular matrix
act as reservoirs of infection through spore seeding
all of the answers are correct
none of the answers are correct
Candida albicans biofilms produce a specialised type of cell that enables persistence. What is this type of cell called?
macrophage cell
persister cell
epithelial cell
yeast cell
hyphal cell
The Candida albicans switch from yeast to hypha is triggered by which of these stimuli?
alkaline pH
osmotic stress
human serum
low oxygen
all of the answers are correct
Which is the least severe mycoses (disease caused by fungi)
superficial
cutaneous
subcutaneous
invasive
Which is the most severe mycoses (disease caused by fungi)
superficial
cutaneous
subcutaneous
invasive
What are the requirements for fungal disease?
exposure
survival & growth of fungus
damage to the host
antibiotics in fungus
What are fungal virulence factors?
fungal attributes that directly or indirectly enhance invasiveness by promoting infection
fungal attributes that only directly enhance invasiveness
fungal attributes that directly or indirectly inhibit invasiveness by promoting infection
fungal attributes that only indirectly enhance invasiveness
What are the virulence factors that promote fungal colonisation?
adhesins
invasins
broad metabolic flexibility
stress resistance
immune evasion
What are virulence factors that damage the host?
morphological transition
secreted hydrolytic enzymes & toxins
stress resistance
immune evasion
adhesins
Select all that is correct about Candida albicans
opportunistic
colonies skin, mouth, genital mucosa, intestinal mucosa
is thermally dimorphic
grow as both yeast and hyphal form in human host
main portal of entries are GI tract, intravascular catheters, genital tract
What are the in vivo challenges for C. albicans
bacterial microbiota
shear forces
chemical and physical stresses
physical barriers
innate immune mechanisms
Commensal bacteria prevent the overgrowth of C. albicans by
competition for adhesion sites
secretion of short chain fatty acids
secretion of quorum sensing molecules
decreased pH from bacterial metabolites
increased attack by macrophages
T or F. C. albicans adhesion to host cells (yeast) is essential to colonisation and survival in host
(a)
T or F. C. albicans interactions usually occur between yeasts and epithelial cells & are mediated by passive forces
(a)
T or F. C. aldbicans adhesion to yeast is more adherent that hyphae
(a)
What are the two main mechanisms of cellular invasion?
induced endocytosis
active penetration
host cell adhesion
covalent attachment
T or F. Induced endocytosis is initiated by binding of C. albicans invasions Ssa1 and/or Als3 to their host receptors
(a)
Select all that are correct about induced endocytosis
occurs via recruitment of clathrin and cytoskeleton reorganisation
forms an invasion pocket
hypha invades pocket
needs a carrier protein to bind
Select all that are correct about active penetration
secreted into invasion pocket created by invading hypha
damages epithelial membranes
triggers danger response signalling pathways
activates epithelial immunity
uses saps, lipases, phospholipases, candidalysin
What are the two main ways that Candida albicans evade the host immune response?
escape from phagocytic cells
biofilm formation
denaturation
tricking the cell into thinking its a friend then BOOM you have a deadly disease in ur body
Why are C. albicans biofilms so hard to eradicate?
extracellular matrix
persister cell
upregulation of drug efflux pumps
increased cell density and stress response
decreased metabolic rate
