Why is fungal taxonomy so complicated?
Because many fungi can reproduce both sexually and asexually and the morphological characteristics of these stages are different.
What are the 4 clinical classifications of fungi?
1 - Yeasts
2 - Molds
3 - Dimorphic fungi
4 - Poisonous mushrooms (homobasidiomycetes) –> mycetism
How do yeast divide?
By binary fission
Why is worrying about chronic infections due to molds nonsensical?
Spores of molds are everywhere, but people don’t just get sick off of them
When would someone be likely to be infected or have bad outcomes with spores of molds?
When profoundly immunocompromised or if allergic to spores
People that are capable of becoming allergic to a broad amount of allergens
Atopic
What is the test to tell if someone is atopic?
A wool sweater is itchy on them
What does dimorphic fungi mean?
Can grow as yeasts and as molds, depending on the culture
Fungi that can produce higher toxins that can kill you, produce psychoactive effects, or make you very sick.
Homobasidiomycetes
What is the meat of the homobasidiomycete mushroom made of?
Densely packed hyphae
What is the scientific explanation for fairy rings (i.e. mushrooms growing in a perfect circle)?
Homobasidiomycete at the center, exsporulate in an explosive fashion on a night without wind. The spores will fall equidistantly from the center, and produce the fairy ring.
Yeast ____ and divided, while molds form _______.
bud
hyphae
Single, unconnected vegetative cells (fungi)
yeasts
Grow similarly to bacteria, but are much larger.
Yeasts
Fungi that reproduce by budding.
yeasts
Fungi that do not sporulate.
yeasts
Fungi used for commerical production of alcohol and citric acid and do not usually pose a hazard to laboratory workers.
yeasts
How do molds grow?
Grow in a complex mass called a mycelium, composed of tubes called hyphae
When hypha filaments are packed densely, the mycelium can appear to be a cohesive tissue. What fungal group has this?
Homobasidiomycetes
How do molds reproduce?
form spores
Aerial hypha
stolon
Fruiting heads = ___________.
Stalk holding up the fruiting heads.
Sporangium/a
sporangiophore
Describe how many spores are released from the mycelium.
Released in INCREDIBLE numbers
How can spores become a contamination hazard?
Can become airborne and present a contamination hazard in labs working on pathogenic molds
Spores are most commonly formed _________ (_________), but can also be produced _________ (_________)
asexually - conidia
sexually - ascospores
What is the most common fungal infection (Causative agent)?
Candida albicans
Most yeast infections are _________.
endogenous
Most yeast infections are endogenous, except for ___________ ____________, which is associated with the excrete of gregarious birds, primarily pigeons?
Cryptococcus neoformans
Cryptococcus neoformans is associated with what?
Excreta of gregarious birds
What does gregarious bird mean?
Birds that flock together
What are predisposing factors to superficial yeast infections?
1 - Wet work - e.g. dishwashers 2 - Pregnancy, oral contraceptives 3 - Diabetes mellitus 4 - Broad spectrym antibiotics 5 - HIV infection, CD4 < 500 6. Dectin-1 (Beta-glucan receptor) deficiency
What does diabetes predispose you to?
Literally everything
What are predisposing factors to deep yeast infections?
1 - Cytotoxic chemotherapy, corticosteroids 2 - Indwelling venous catheters 3 - Broad spectrum antibiotics 4 - Intravenous drug abuse 5 - HIV infection, CD4 < 200
Why can safe injection sites be a meme?
because the drugs are not supervised
Most common yeast causing infection.
Candida albicans
Candida albicans is part of the normal flora where?
oropharynx, vagina, bowel and skin
What does Candida albicans cause?
acute and chronic superficial infections of:
the skin - diaper rash, balanitis, intertriginous areas
nails - paronychia
mucous membranes - thrush, vaginitis
UTI
Candida albicans can cause severe disease in who? What are they?
Immuncompromised patients
Esophagitis
pyelonephritis
sepsis
What is balanitis?
superficial infection of the glans of the penis
What are intertriginous areas?
skin on skin
How would one describe a C. albicans rash?
Contiguous, red inflammed mass with silvery whiteish sheen
the defining feature are the satellite lesions
What does thrush look like?
adherent white plaques with erythematous base
What kind of odour may you smell with thrush?
freshly baked bread
What is the major virulence factor of C. neoformans?
Capsule
What is used to screen CSF samples for C. neoformans?
India ink test - stands out in darkfield microscopy
also latex agglutination test for antigens (positive)
What can C. neoformans cause?
Diffuse pulmonary infection (usually asymptomatic)/progressive pulmonary disease with abscesses
or disseminated disease
What are the risk factors for disseminated disease?
HIV, malignancy, corticosteroids
What can C. neoformans cause, but very rarely?
What can we use to get rid of it?
Intracerebral mass lesions (cryptococcomata)
oral fluconazole
C. neoformans can cause chronic meningitis in AIDS patients, but this meningitis is atypical. How?
will only have mild headache, but can walk around
unlike the usual coma which can occur with normal meningitis