Mycology I and II - Introduction to Medical Mycology and Opportunistic Invasive Fungi

Question 1

Fungi are in the kingdom ____________.

Answer 1

eucarya

Question 2

Fungi are considered ________-trophs.

Answer 2

osmo

Question 3

Germ tubes ultimately become __________.

Answer 3

pseudohyphae

Question 4

Why does administration of antibiotics frequently cause fungal infection?

Answer 4

Fungi secrete antibiotics to kill bacteria, so exogenous antibiotics essentially do the work that fungus would need to do itself.

Question 5

Cryptococcus neoformans is common in which populations?

Answer 5

All types of immunocompromised people:

• HIV
• Organ transplant

Question 6

Which three drugs treat Cryptococcal meningitis?

Answer 6

• 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)

Question 7

What is unique about the meningitis caused by Cryptococcus?

Answer 7

It doesn’t induce inflammation as much as bacteria would, but it can clog the draining sites of CSF and cause increased ICP.

Question 8

How is Cryptococcus neoformans transmitted?

Answer 8

It is usually inhaled from pigeon or koala stool (like the pigeons in the crypt and the archaeologist coughing).

Question 9

Cryptococcal skin infections can mimic _____________.

Answer 9

Molluscum contagiosum (small, swollen, pearly papules)

Question 10

Name six tests that can identify Cryptococcus.

Answer 10

• 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.)

Question 11

A shocking study in the 1990s showed that ___________ was the fourth most common cause of nosocomial bloodstream infections.

Answer 11

Candida albicans

Question 12

Candida bacteremia has a ____________ mortality.

Answer 12

horrible (40%)

Note: it’s thought that Candida is only an indicator of how sick a person is, not because Candida causes death.

Question 13

Candida that is resistant to amphotericin can be treated with ________________.

Answer 13

caspofungin (like the old man’s cap in the Candida Sketch)

Question 14

Which fungi can cause tricuspid endocarditis?

Answer 14

Candida (remember the triple roof on the Canadian playground?)

Question 15

The beta-1,3-D glucan test has ____________.

Answer 15

low sensitivity and low specificity

Question 16

True or false: Aspergillus is a part of the normal human biome.

Answer 16

False. Though it is omnipresent.

Question 17

Candida can form fungal balls in the __________.

Answer 17

urine, whereas Aspergillus forms them in the lungs

Question 18

Chest radiographs of someone with Aspergillus pneumonia can show the _________ sign.

Answer 18

halo

Question 19

In everyday life, Penicillium grows on __________.

Answer 19

oranges; it’s the green mold that forms on an orange

Question 20

Mucorales metabolizes ________________.

Answer 20

iron, acid, and glucose

Think of the Ketone auto parts and jar of candies in the shop.

Question 21

Uniquely, the Mucorales fungi can be treated with ______________.

Answer 21

deferoxamine

Question 22

______________ almost always presents in diabetics.

Answer 22

Rhinocerebral mucormycosis

Question 23

What two things can cause bilateral eye ecchymoses?

Answer 23

• Basilar skull fractures

* Cavernous sinus thrombosis

Question 24

Pulmonary infarcts – which are usually wedge-shaped –can be caused by _______________.

Answer 24

Mucor or Aspergillus, both of which invade blood vessels and can infarct lung tissue

Question 25

Dermatiaceous moulds are also called __________.

Answer 25

black moulds

Question 26

Dematiacous molds produce _______________.

Answer 26

melanin (hence turning black)

Question 27

What is the main difference between fungi and plants?

Answer 27

Fungi do not have chlorophyll.

Question 28

Mycelium are _______________.

Answer 28

large collections of hyphae

Question 29

________________ binds to chitin and can fluorescently stain fungi.

Answer 29

Calcofluor

Question 30

Cryptococcus gattii is found on ____________.

Answer 30

eucalyptus trees

Question 31

True or false: Cryptococcus is transmitted by conidiophores.

Answer 31

False. It is not a dimorphic fungus, so it is always a yeast.

Question 32

You see a fungus dividing as yeast in someone’s lungs. How might you tell if it is Cryptococcus or Blastomyces?

Answer 32

Cryptococcus divides by narrow-based budding, while Blastomyces divides by broad-based budding.

Question 33

The most distinct feature of Cryptococcus under microscopic examination is ______________.

Answer 33

its thick polysaccharaide capsule

Question 34

Why does Cryptococcus localize to the brain?

Answer 34

Cryptococcus produces melanin, and the high levels of dopamine in the brain allow it to survive.

Question 35

What did the study on Vancouver Island show?

Answer 35

That Cryptococcus has an incubation period of several months

Question 36

What three strains of Candida account for the majority of human infections?

Answer 36

• C. albicans
• C. parapsilosis
• C. glabrata

Question 37

Typically, the only people in whom Candida becomes invasive have what characteristics?

Answer 37

• Immunocompromisation

* Invasive medical procedures

Question 38

All patients with invasive Candida fungemia must undergo a _____________ examination.

Answer 38

ophthalmic

Candida can infect the eye and cause endophthalmitis.

Question 39

_______________ grows as septate hyphae in vivo and in vitro.

Answer 39

Aspergillus fumigatus

Question 40

Which Aspergillus disease does not result from infection?

Answer 40

Allergic bronchopulmonary Aspergillosis

Question 41

Which fungus macroscopically resembles mouse fur?

Answer 41

Mucor (think murine = mucor)

Question 42

Why was PCP originally classified as a protozoan?

Answer 42

It lacks ergosterol.

Question 43

Explain why PCR and culture are not used to diagnose PCP?

Answer 43

• PCR is so sensitive it might pick up non-infective samples of PCP.
• PCP does not grow in culture.

Question 44

Black molds typically cause disease in what population?

Answer 44

The immunocompromised (and even then it’s rare)

Question 45

______________ has extremely rapid growth.

Answer 45

Mucor