Lecture 35 - Introduction to Fungal Disease

Question 1

which innate immune component CANNOT directly induce microbe lysis

a. NK cell
b. neutrophil
c. complement system
d. antimicrobial molecules

Answer 1

a. NK cell

Question 2

which T helper type is important for INTRACELLULAR infection

Answer 2

Th1

Question 3

molecules that are produced by microbes and cause disease are called

Answer 3

virulence factors

Question 4

which is the vegetative form of a fungus

Answer 4

c. hypha

Question 5

which is the most common inflammatory reaction to fungal infections

a. eosinophilic
b. neutrophilic
c. pyogranulomatous
d. abscess

Answer 5

c. pyogranulomatous

Question 6

why do you need to inform the diagnostic lab that you suspect fungal infection when you submit your samples

Answer 6

the cultured form is infectious to people

Question 7

which pathogenic yeast has a thick capsule that prevents an inflammatory response

a. candida albicans
b. histoplasma capsulatum
c. blastomyces dermatitidis
d. cryptococcus neoformans

Answer 7

d. cryptococcus neoformans

Question 8

which pathogen is an aquatic oocyte

Answer 8

pythium insidiosum

Question 9

which of these fungi is contagious

a. microsporum canis
b. sporothrix schenckii
c. histoplasma capsulatum
d. blastomyces dermatitidis

Answer 9

a. microsporum canis

Question 10

T/F: mycotoxins are virulence factors produced by infectious fungi

Answer 10

FALSE - fungi cannot be infectious

Question 11

The organ/tissue most commonly affected by mycotoxins is the

Answer 11

liver

Question 12

what is a fungus

Answer 12

• heterotrophic, aerobic, nonmotile eukaryotes
• abundant in soil, vegetation, water

Question 13

what are the two classifications of fungal existence

Answer 13

1. saprophytic
2. parasitic

Question 14

T/F: fungi are not contagious except for ringworm and sporotrichosis

Answer 14

TRUE

Question 15

what is the job of the complex, carbohydrate-based cell wall of fungi

Answer 15

• prevents lysis (osmotic or complement)
• protects from mechanical injury

Question 16

mold vs. yeast

Answer 16

mold - masses of multicellular hyphae

yeast - single cells that reproduce by budding

Question 17

describe hyphae

Answer 17

• vegetative/growing form of mold
• too big for phagocytosis
• asexual spores
• resistant to chemical/physical agents

Question 18

describe yeasts

Answer 18

• oval to spherical
• reproduce by budding

Question 19

describe candida albicans

Answer 19

• inhabits mucous membranes
• disease in the immunocompromised or microbiota-unbalanced host
• nonpathogenic oval budding yeasts

Question 20

what two factors can contribute to candida albicans overgrowth

Answer 20

1. antibiotic overuse
2. prolonged steroid/hormone therapy

Question 21

describe malassezia pachydermatis

Answer 21

• opportunistic infection of skin, external ear canal
• oval, broad-based budding yeast

Question 22

what is dimorphic fungi

Answer 22

grown as hyphae in the environment and converted to yeast in tissues at body temp

Question 23

what form of classification is seen in diagnostic labs

Answer 23

asexual spores/structures

Question 24

what form of classification is NOT demonstrated in medically important fungi

Answer 24

sexual spores/structure

Question 25

what do innate defenses do to spores and other fungal elements

Answer 25

1. inhibit 2. phagocytize 3. kill

Question 26

T/F: fungi do not usually cause disease in immunocompetent animals

Answer 26

TRUE

Question 27

What are fungal virulence factors

Answer 27

1. adhesins 2. enzymes 3. melanin (an antioxidant that reduces the toxicity of agents in phagolysosome) 4. mannitol (impairs phagolysosomal degradation) 5. cell wall glycoproteins have endotoxin-like activity

Question 28

What are the different ways to diagnose fungal infections

Answer 28

1. direct exam (diff quick, wright's) 2. histopathology 3. antigen detection 4. fungal isolation 5. PCR 6. Marix-Assisted Laser Desorption Ionization - Time of Flight 7. ELISA

Question 29

what fungal diagnostic test poses risk to humans

Answer 29

fungal isolation

Question 30

what are the two tests used in histopathology

Answer 30

1. Periodic Acid-Schiff Reaction 2. Grocott/Gomori Methenamine Silver

Question 31

if fungal hyphae are too big, how does the immune system target them?

Answer 31

via pyogranulomatous response

Question 32

what are the 4 types of fungal diseases

Answer 32

1. systemic mycoses 2. sq or deep mycoses 3. cutaneous mycoses 4. mycotoxicoses

Question 33

describe Histoplasma capsulatum (type, species, spread, evasion mechanism)

Answer 33

type: systemic species: cats and dogs spread: via alveolar macrophages to lymph evasion mechanism: prevents lysis in phagolysosome by enzyme inhibition

Question 34

describe cryptococcus neoformans (type, species, spread, evasion mechanism)

Answer 34

type: systemic species: cats, dogs, cattle, horses, humans spread: from nasopharynx to CNS by direct extension evasion mechanism: thick capsule *narrow-based budding

Question 35

describe aspergillus fumigatus (type, species, spread, etc.)

Answer 35

type: systemic species: all spread: inhalation/ingestion/injection spread in macrophages through vessels evasion mechanism: secrete toxins that slow mucociliary apparatus

Question 36

describe sporothrix schenckii (type, species, spread, etc.)

Answer 36

type: sq species: cats, dogs, horses, humans spread: cutaneolymphatic and local proliferation evasion: capsules

Question 37

describe pythium insidisum (type, species, spread, etc.)

Answer 37

type: sq species: horses, cattle, dogs, cats *aquatic oocyte

Question 38

what is the proper treatment for pythium insidiosum

Answer 38

aggressive surgical excision with wide margins

Question 39

what is also known as "kunkers" in horses

Answer 39

pythium insidiosum

Question 40

describe dermatophytoses (type, species, spread, etc.)

Answer 40

type: cutaneous spread: stratum corneum infection, hyphae branches to arthroconidia and infect nearby surfaces *ringworm

Question 41

What is Microsporum canis

Answer 41

- most common cause of ringworm in dogs and cats - early response: scruffy, hair loss, hypertrophy of stratum corneum - 2nd week: inflammation, antibody and cell-mediated hypersensitivity

Question 42

mycotoxin

Answer 42

- secondary metabolite of fungus - disease depends on the individual mycotoxin - no treatment

Question 43

describe aflatoxin B1 (type, species, spread, etc.)

Answer 43

type: mycotoxin spread: ingestion of contaminated feedstuffs and conversion via cytochrome P450 *binds to cellular DNA, RNA, or proteins

Question 44

describe phomopsins or lupinosis (type, species, effect)

Answer 44

type: mycotoxin species: cattle, sheep, horses effect: hepatic dysfunction (lipidosis)

Question 45

describe amantia (type, species, spread, etc.)

Answer 45

type: mycotoxin (poison mushrooms) effect: inhibits RNA poly. II, liver necrosis, irreversible disruption of actin

Question 46

what are the 2 contagious fungi

Answer 46

Microsporum canis and Sporothrix schenckii