04b: Fungi

Question 1

List the three major mechanisms by which fungi can cause disease in people:

Answer 1

1. Toxin
2. Allergy (rhinitis/asthma)
3. Direct infection

Question 2

T/F: Like plants, fungi have chlorophyll.

Answer 2

False

Question 3

Fungi that derive nourishment from dead/composing organic material have (X) existence.

Answer 3

X = saprophytic

Question 4

Fungi that use material from living organism in mutually beneficial way have (X) existence.

Answer 4

X = symbiotic

Question 5

Fungi that use material from living organism for its benefit (but is neither beneficial nor harmful for host) have (X) existence.

Answer 5

X = commensal

Question 6

Fungi that use material from living organism in manner that harms host have (X) existence.

Answer 6

X = parasitic

Question 7

Fungi are (prok/euk). They (have/lack) nucleus/nuclear membrane and organelles, have (X) ribosome, and (have/lack) cell wall.

Answer 7

Eukaryotic;
Have (golgi)
X = 80S
Have rigid cell wall

Question 8

T/F: Fungal cell wall structure similar to bacterial cell wall.

Answer 8

False - contains chitin, mannan, and beta-glucan

Question 9

Medically important fungi can be either moist, waxy colonies called (X) or branching tubular filaments called (Y)

Answer 9

X = yeast
Y = hyphae (mass = "mold")

Question 10

(Yeast/hyphae) cells are round/oval and typically reproduce by which mechanism(s)?

Answer 10

Yeast;

Budding (small outgrowth) or fission (splitting into equally-sized daughter cells)

Question 11

(X) are elongated (yeasts/hyphae) with constrictions between cells. Looks like chain of sausages.

Answer 11

X = pseudohyphae

Yeasts

Question 12

T/F: Hyphae can be either septate or aseptate.

Answer 12

True

Question 13

How to molds reproduce?

Answer 13

Hyphae produce spores (conidia)

Question 14

Thermally dimorphic fungi appear as (X) in environment and as (Y) in mammals. What stimulates this phase-transition?

Answer 14

X = mold
Y = yeast

In-vivo conditions (esp 37oC)

Question 15

T/F: Gram stain is useless for all fungi.

Answer 15

False - all except Candida (gram-pos)

Question 16

Due to their (X), fungi are resistant to degradation by hot alkali. Thus, (Y) prep can be used to visualize fungi in lab.

Answer 16

X = cell wall
Y = KOH

Question 17

(X) stain is good for visualizing fungi, which stain black.

Answer 17

X = Silver

Question 18

(X) stain is good for visualizing fungi, which stain red.

Answer 18

X = PAS

Question 19

When fungal infection is suspected, specimens should be plated on special medium, (X) agar.

Answer 19

X = Sabouraud;

Question 20

(X) are (superficial/subcutaneous/systemic) mycoses (mold) that can invade keratinized tissues by virtue of their ability to metabolize (Y).

Answer 20

X = dermatophytosis
Superficial;
Y = keratin

Question 21

Most common sites of dermatophytosis.

Answer 21

Scalp, beard, feet, groin, nails

Question 22

“Tinea pedis” aka “athlete’s foot” is (superficial/subcutaneous/deep) mycosis caused by (X) molds.

Answer 22

Superficial;

X = dermatophytosis

Question 23

T/F: Dermatophytosis can be treated topically.

Answer 23

True

Question 24

(X) is a common, superficial fungal infection that produces (hypo/hyper)-pigmented lesions, generally on trunk/proximal limbs.

Answer 24

X = tinea versicolor

Either hyper or hypo-pigmented lesions

Question 25

Dandruff is (X) of the scalp. This is primarily an inflammatory reaction to (Y) species. It presents with which symptoms?

Answer 25

``` X = seborrheic dermatitis Y = Malassezia (fungal) ``` Erythema, scaling, itching

Question 26

"Madura foot" aka (X), is (superficial/subcutaneous/systemic) mycosis. It's a(n) (acute/chronic) infection that presents with which symptoms?

Answer 26

X = Mycetoma Subcutaneous; Chronic Swelling, nodules, sinus tracts

Question 27

How can dermatophytes be spread to humans?

Answer 27

1. Other humans 2. Soil 3. Animals

Question 28

Onychomycosis is what kind of (bacterial/fungal) infection? It's more commonly found in which population?

Answer 28

Fungal; superficial mycosis (dermatophytosis) of (toe) nails More common in elderly population

Question 29

Which dermatophytosis (superficial mycosis) is more commonly found in pediatric population?

Answer 29

Tinea capitus (of scalp)

Question 30

Which fungal species responsible for Tinea versicolor?

Answer 30

Malassezia species

Question 31

(X) is the most common species of Candidiasis. The agents form (yeast/hyphae) in tissue.

Answer 31

X = Candida albicans Yeasts, hyphae, and pseudohyphae

Question 32

Unlike most systemic mycoses, which are acquired via (X), (Y) infections are generally acquired via (Z).

Answer 32

``` X = inhalation of airborne spores Y = Candida Z = endogenous infection ```

Question 33

Mucocutaneous candidiasis is seen in patients with (X).

Answer 33

X = defects in T cell-mediated immunity, diabetes, on broad spectrum antibiotics

Question 34

Disseminated candidiasis is seen in patients with (X).

Answer 34

X = neutropenia, IV cath, surgery

Question 35

"Thursh" aka (X) is often the first clinical manifestation of (Y).

Answer 35

``` X = oral (mucocutaneous) candidiasis Y = HIV ```

Question 36

Which two agents are responsible for Cryptococcosis?

Answer 36

1. Cryptococcus neoformans | 2. Cryptococcus gattii

Question 37

(X) is the only medically important fungus with a capsule, which circulates in (Y) body compartments and is useful for diagnosis.

Answer 37

X = Cryptococcus; Y = blood and CSF

Question 38

Which fungal agent is found worldwide, with high concentrations in soil, bird droppings, and rotting wood?

Answer 38

Cryptococcus

Question 39

Cryptococcus has strong association with (X) disorders.

Answer 39

X = T-cell immunity (esp. AIDS) Also transplants

Question 40

(X) is the most common clinical presentation of C. neoformans.

Answer 40

X = meningitis

Question 41

Patient with meningitis. You suspect Cryptococcus (X) infection. What could you measure to verify this?

Answer 41

X = neoformans CSF would have high protein, low glucose (maybe), and be positive for Cryptococcal Ag

Question 42

Which drug would you use for extensive mucocutaneous candidiasis?

Answer 42

Fluconazole And, if possible, eliminate predisposing condition (ex: discontinue broad spectrum antibiotics)

Question 43

(X) is the most common fungus in the environment. What is the spectrum of disease conditions/mechanisms it can cause?

Answer 43

X = aspergillosis Allergic, Aspergilloma, Invasive

Question 44

Patient has pre-existing pulmonary cavity. You suspect (X) species of (bacteria/fungus) is residing in that cavity. What are you afraid that agent will do?

Answer 44

X = aspergillosis Fungus Can either chill or invade vessels (hemorrhagic infarction)

Question 45

Patient on chemo (weak immune system) is at risk for (X) invasive fungal infection. With very low (Y) WBCs, infection by this agent can have pt mortality over 50%!

Answer 45

``` X = aspergillosis Y = PMNs ```

Question 46

Black, necrotic lesion is classic presentation of (X) fungal infection. Which patients have predisposition?

Answer 46

X = mucormycosis Diabetic ketoacidosis, neutropenia

Question 47

(X) is the most common life-threatening infection in AIDS patients in US. What's the infectious agent responsible?

Answer 47

X = pneumocystis pneumonia Pneumocystis jiroveci

Question 48

Patient with pneumocystosis (PCP) will have which clinical presentation?

Answer 48

Pneumonia (fever, non-productive cough, SOB); | Chest X-ray will show diffuse interstitial infiltrates

Question 49

T/F: Pneumocystis jiroveci cannot be cultured.

Answer 49

True

Question 50

(X) fungal agent is endemic in Ohio and Mississippi River valleys, Caribbean, and Central America. Exposure to (Y) is risk factor. (Z) patients are particularly susceptible.

Answer 50

``` X = Histoplasma capsulatum Y = bird/bat droppings Z = AIDS ```

Question 51

Histoplasmosis diagnosis in immunocompetent patients is via (X) test. And in AIDS patients is via (Y) test.

Answer 51

``` X = serology Y = urine antigen ```

Question 52

(X), also known as "valley fever", is endemic in San Joaquin valley, SW US, and parts of Latin America. Which fungal agents are responsible?

Answer 52

X = Coccidioides 1. Coccidioides immitis 2. Coccidioides posadasii

Question 53

(X) fungal species forms mature spherule in lung, filled with (Y). If the spherule bursts, all the (Y) have which fate?

Answer 53

``` X = coccidioides Y = endospores ``` Spread and can develop into new spherules

Question 54

T/F: Coccidioides infection doesn't occur in immunocompetent patients.

Answer 54

False - but more common in those with impaired CMI (esp AIDS)

Question 55

(X) fungal agent has multiple buds that look like "pilot wheel" or Mickey Mouse. Where is this infection endemic?

Answer 55

X = Paracoccidioides brasiliensis South America (esp Brazil and Colombia)

Question 56

(X) fungal agent is mold in (nature/tissue) and large, broad-based yeast buds in (nature/tissue). It's endemic in SE and Central U.S. as well as the Great Lakes.

Answer 56

X = Blastomyces dermatitidis; | Nature; tissue

Question 57

Being pricked by rose thorn puts you most at risk for which fungal infection?

Answer 57

Sporothrix schenckii

Question 58

(X) fungal infection is endemic in areas of SE Asia and nearly all cases are seen in (Y) patients. Unlike most yeasts, reproduction of this agent is via (budding/fission).

Answer 58

``` X = Talaromyces (penicillium) marneffei Y = AIDS ``` Fission

Question 59

Colonization of (X) species of fungus is common in humans.

Answer 59

X = candida