05 - Mycology

Question 1

Identify: fungal infection associated with pseudomembranous pharyngitis:

Answer 1

Candida

Question 2

Two basic fungal forms:

Answer 2

1. yeast - single-celled

2. mold - with hyphal elements

Question 3

Term: the ability to reproduce as one of either of the two basic forms, depending on the temperature:

What forms are assumed in culture media and in live tissues in these kinds of organisms?

Answer 3

thermal dimorphism

• molds on culture medium at room temperature
• yeasts on live, infected tissue

Question 4

Two types of host response to fungal infection:

Answer 4

• granulomatous

- pyogenic

Question 5

• toxin of Amanita:

- What is the effect?

Answer 5

• amanitin and phylloidin

- liver necrosis

Question 6

• toxin of Aspergillus flavus:

- What is the effect?

Answer 6

• aflatoxin

- G:C->T:A mutation, leading to liver cancer

Question 7

term for allergic reaction to spores of Aspergillus fumigatus:

Answer 7

allergic bronchopulmonary aspergillosis

Question 8

Identify: agar used in the culture of fungi:

Answer 8

Sabouraud agar - low pH inhibits growth of bacteria

Question 9

This stain binds to the complex carbohydrate cell wall of fungi and lights up a bright blue white color:

Answer 9

Calcofluor white

Question 10

This stain is primarily used for negative staining.

-What fungus is diagnosed using this stain?

Answer 10

Nigrosin

-Cryptococcus neoformans

Question 11

Enumerate 3 important dermatophytoses:

Answer 11

1. Microsporum canis
2. Trichophyton tonsurans
3. Epidermophyton floccosum

Question 12

Another name for dermatophytoses:

Answer 12

ring worms

Question 13

Term: an inflammatory reaction to dermatophytosis at a cutaneous site distant from the primary infection

Answer 13

dermatophytid reaction

Question 14

How to diagnoses dermatophytoses:

Answer 14

• 10% KOH
• Sabouraud agar
• Wood lamp: green fluorescence

Question 15

Treatment of dermatophytoses:

Answer 15

• local antifungal cream

- keep skin dry

Question 16

• Identify: superficial skin infection presenting with hypopigmented areas.
• What causes the hypopigmentation?
• What fungal organism causes this condition?
• Treatment:

Answer 16

• Tinea versicolor
• azoleic acid
• Malasseizia furfur
• miconazole

Question 17

Identify: This organism causes fungemia in premature infants on IV nutrition:

Answer 17

Malassezia furfur

Question 18

Mechanism of transmission of Sporotrichosis:

Answer 18

rose thorn prick

Question 19

Another name for sporotrichosis:

Answer 19

Rose gardener’s disease

Question 20

Treatment of sporotrichosis:

Answer 20

itraconazole, or potassium iodide

Question 21

Enumerate: the two morphologies of Coccidioides immitis, in which settings:

Answer 21

• mold in soil

- spherule in tissue

Question 22

another term for Coccidioidomycosis:

Answer 22

Desert Rheumatism, a.k.a. San Joaquin valley fever

Question 23

Mechanism of transmission of Coccidiodes:

Answer 23

inhalation of arthrospores

Question 24

Symptoms of Desert Rheumatism:

Answer 24

Flu-like symptoms:

• fever
• arthralgia
• malaise
• cough/coryza
• headache

Question 25

Two types of asexual spores in Histoplasma capsulatum:

Answer 25

- tuberculate macroconidia | - microconidia

Question 26

mechanism of transmission of Histoplasma:

Answer 26

-inhalation of airborne microconidia

Question 27

describe the pathogenesis of Histoplasma:

Answer 27

Inhaled histoplasma microconidia develop into yeasts inside macrophages, and the spreads to the liver and the spleen

Question 28

mechanism of transmission of Blastomyces dermatitidis

Answer 28

inhalation of conidia

Question 29

- Paracoccidioides brasiliensis preferentially infects which subgroup of the population? - Explain

Answer 29

- preferentially infects males | - Estrogen and progesterone are found to be protective

Question 30

mechanism of transmission of Paracoccidioides brasiliensis

Answer 30

inhalation of conidia

Question 31

morphologies of Candida albicans in serum, and in culture

Answer 31

- germ tubes in serum | - chlamydo-spores in culture

Question 32

Enumerate: diseases of Candida in the immunocompetent (give 3)

Answer 32

- oral thrush - vulvovaginitis - onychomycosis

Question 33

Manifestion of Candida infection in the immunocompromised:

Answer 33

pseudomembranous esophagitis

Question 34

Identify: most common cause of fungal encephalitis

Answer 34

Cryptococcus neoformans

Question 35

Enumerate: Diagnostic tests for Cryptococcus

Answer 35

1. India ink preparation (negative staining) | 2. CALAS (Cryptococcal antigen latex agglutination system)

Question 36

How is cryptococcus transmitted?

Answer 36

grows abundantly in soil with lots of bird dropping; inhalation of airborne yeast cells

Question 37

DOC for cryptococcal encephalitis:

Answer 37

amphotericin B + flucytosine

Question 38

Morphologies of Aspergillus fumigatus:

Answer 38

exist only as molds!

Question 39

How is Aspergillus transmitted?

Answer 39

inhalation of airborne conidia

Question 40

Term for fungus balls:

Answer 40

Aspergilloma

Question 41

Identify: Aspergillosis with asthmatic symptoms with expectoration of brownish bronchial plugs

Answer 41

allergic bronchopulmonary aspergillosis (ABPA)

Question 42

Identify: organisms in Mucormycosis:

Answer 42

Rhizopus and mucor

Question 43

Clinical presentation of mucormycosis:

Answer 43

rhino-orbital-cerebral infection with eschar formation

Question 44

Enumerate: these (3) patients are at high risk for infection with Rhizopus and mucor

Answer 44

- Burn patients - DKA patients - leukemia

Question 45

The major surface glycoproteins of this fungus undergoes programmed rearrangements:

Answer 45

Pneumocystis jiroveci

Question 46

Diagnostic test for Pneumocystis jiroveci

Answer 46

Bronchoalveolar washings, then - toluidine blue - methenamine silver stain

Question 47

mechanism of transmission of Pneumocystis jiroveci:

Answer 47

inhalation of cysts

Question 48

At what CD4 count does Pneumocystis pneumonia occur?

Answer 48

CD4 < 200

Question 49

Identify: what is the most common AIDS-defining illness?

Answer 49

Pneumocystis jiroveci pneumonia

Question 50

DOC for Pneumocystis jiroveci pneumonia:

Answer 50

Trimethoprim-sulfamethoxazole