Mycology I and II - Introduction to Medical Mycology and Opportunistic Invasive Fungi Flashcards
Fungi are in the kingdom ____________.
eucarya
Fungi are considered ________-trophs.
osmo
Germ tubes ultimately become __________.
pseudohyphae
Why does administration of antibiotics frequently cause fungal infection?
Fungi secrete antibiotics to kill bacteria, so exogenous antibiotics essentially do the work that fungus would need to do itself.
Cryptococcus neoformans is common in which populations?
All types of immunocompromised people:
- HIV
- Organ transplant
Which three drugs treat Cryptococcal meningitis?
- First: amphotericin B and flucytosine (think of the flute player and the frog on the wall of the crypt)
- Second: fluconazole (think of the pinecone hieroglyphic and the flying monkeys with the helmet)
What is unique about the meningitis caused by Cryptococcus?
It doesn’t induce inflammation as much as bacteria would, but it can clog the draining sites of CSF and cause increased ICP.
How is Cryptococcus neoformans transmitted?
It is usually inhaled from pigeon or koala stool (like the pigeons in the crypt and the archaeologist coughing).
Cryptococcal skin infections can mimic _____________.
Molluscum contagiosum (small, swollen, pearly papules)
Name six tests that can identify Cryptococcus.
- India ink (vat of dark liquid in the crypt)
- CRAG: Cryptococcal antigen
- CGB agar, which will turn blue
- Growth on blood agar
- Growth on birdseed agar, which will turn black (because of melanin production)
- Gram stain, which will show mild reddish staining
(To help remember the birdseed agar, just think of the pigeon droppings.)
A shocking study in the 1990s showed that ___________ was the fourth most common cause of nosocomial bloodstream infections.
Candida albicans
Candida bacteremia has a ____________ mortality.
horrible (40%)
Note: it’s thought that Candida is only an indicator of how sick a person is, not because Candida causes death.
Candida that is resistant to amphotericin can be treated with ________________.
caspofungin (like the old man’s cap in the Candida Sketch)
Which fungi can cause tricuspid endocarditis?
Candida (remember the triple roof on the Canadian playground?)
The beta-1,3-D glucan test has ____________.
low sensitivity and low specificity
True or false: Aspergillus is a part of the normal human biome.
False. Though it is omnipresent.
Candida can form fungal balls in the __________.
urine, whereas Aspergillus forms them in the lungs
Chest radiographs of someone with Aspergillus pneumonia can show the _________ sign.
halo
In everyday life, Penicillium grows on __________.
oranges; it’s the green mold that forms on an orange
Mucorales metabolizes ________________.
iron, acid, and glucose
Think of the Ketone auto parts and jar of candies in the shop.
Uniquely, the Mucorales fungi can be treated with ______________.
deferoxamine
______________ almost always presents in diabetics.
Rhinocerebral mucormycosis
What two things can cause bilateral eye ecchymoses?
- Basilar skull fractures
* Cavernous sinus thrombosis
Pulmonary infarcts – which are usually wedge-shaped –can be caused by _______________.
Mucor or Aspergillus, both of which invade blood vessels and can infarct lung tissue
Dermatiaceous moulds are also called __________.
black moulds
Dematiacous molds produce _______________.
melanin (hence turning black)
What is the main difference between fungi and plants?
Fungi do not have chlorophyll.
Mycelium are _______________.
large collections of hyphae
________________ binds to chitin and can fluorescently stain fungi.
Calcofluor
Cryptococcus gattii is found on ____________.
eucalyptus trees
True or false: Cryptococcus is transmitted by conidiophores.
False. It is not a dimorphic fungus, so it is always a yeast.
You see a fungus dividing as yeast in someone’s lungs. How might you tell if it is Cryptococcus or Blastomyces?
Cryptococcus divides by narrow-based budding, while Blastomyces divides by broad-based budding.
The most distinct feature of Cryptococcus under microscopic examination is ______________.
its thick polysaccharaide capsule
Why does Cryptococcus localize to the brain?
Cryptococcus produces melanin, and the high levels of dopamine in the brain allow it to survive.
What did the study on Vancouver Island show?
That Cryptococcus has an incubation period of several months
What three strains of Candida account for the majority of human infections?
- C. albicans
- C. parapsilosis
- C. glabrata
Typically, the only people in whom Candida becomes invasive have what characteristics?
- Immunocompromisation
* Invasive medical procedures
All patients with invasive Candida fungemia must undergo a _____________ examination.
ophthalmic
Candida can infect the eye and cause endophthalmitis.
_______________ grows as septate hyphae in vivo and in vitro.
Aspergillus fumigatus
Which Aspergillus disease does not result from infection?
Allergic bronchopulmonary Aspergillosis
Which fungus macroscopically resembles mouse fur?
Mucor (think murine = mucor)
Why was PCP originally classified as a protozoan?
It lacks ergosterol.
Explain why PCR and culture are not used to diagnose PCP?
- PCR is so sensitive it might pick up non-infective samples of PCP.
- PCP does not grow in culture.
Black molds typically cause disease in what population?
The immunocompromised (and even then it’s rare)
______________ has extremely rapid growth.
Mucor
