Lecture 35 - Introduction to Fungal Disease Flashcards
which innate immune component CANNOT directly induce microbe lysis
a. NK cell
b. neutrophil
c. complement system
d. antimicrobial molecules
a. NK cell
which T helper type is important for INTRACELLULAR infection
Th1
molecules that are produced by microbes and cause disease are called
virulence factors
which is the vegetative form of a fungus
c. hypha
which is the most common inflammatory reaction to fungal infections
a. eosinophilic
b. neutrophilic
c. pyogranulomatous
d. abscess
c. pyogranulomatous
why do you need to inform the diagnostic lab that you suspect fungal infection when you submit your samples
the cultured form is infectious to people
which pathogenic yeast has a thick capsule that prevents an inflammatory response
a. candida albicans
b. histoplasma capsulatum
c. blastomyces dermatitidis
d. cryptococcus neoformans
d. cryptococcus neoformans
which pathogen is an aquatic oocyte
pythium insidiosum
which of these fungi is contagious
a. microsporum canis
b. sporothrix schenckii
c. histoplasma capsulatum
d. blastomyces dermatitidis
a. microsporum canis
T/F: mycotoxins are virulence factors produced by infectious fungi
FALSE - fungi cannot be infectious
The organ/tissue most commonly affected by mycotoxins is the
liver
what is a fungus
- heterotrophic, aerobic, nonmotile eukaryotes
- abundant in soil, vegetation, water
what are the two classifications of fungal existence
- saprophytic
- parasitic
T/F: fungi are not contagious except for ringworm and sporotrichosis
TRUE
what is the job of the complex, carbohydrate-based cell wall of fungi
- prevents lysis (osmotic or complement)
- protects from mechanical injury
mold vs. yeast
mold - masses of multicellular hyphae
yeast - single cells that reproduce by budding
describe hyphae
- vegetative/growing form of mold
- too big for phagocytosis
- asexual spores
- resistant to chemical/physical agents
describe yeasts
- oval to spherical
- reproduce by budding
describe candida albicans
- inhabits mucous membranes
- disease in the immunocompromised or microbiota-unbalanced host
- nonpathogenic oval budding yeasts
what two factors can contribute to candida albicans overgrowth
- antibiotic overuse
- prolonged steroid/hormone therapy
describe malassezia pachydermatis
- opportunistic infection of skin, external ear canal
- oval, broad-based budding yeast
what is dimorphic fungi
grown as hyphae in the environment and converted to yeast in tissues at body temp
what form of classification is seen in diagnostic labs
asexual spores/structures
what form of classification is NOT demonstrated in medically important fungi
sexual spores/structure
what do innate defenses do to spores and other fungal elements
- inhibit
- phagocytize
- kill
T/F: fungi do not usually cause disease in immunocompetent animals
TRUE
What are fungal virulence factors
- adhesins
- enzymes
- melanin (an antioxidant that reduces the toxicity of agents in phagolysosome)
- mannitol (impairs phagolysosomal degradation)
- cell wall glycoproteins have endotoxin-like activity
What are the different ways to diagnose fungal infections
- direct exam (diff quick, wright’s)
- histopathology
- antigen detection
- fungal isolation
- PCR
- Marix-Assisted Laser Desorption Ionization - Time of Flight
- ELISA
what fungal diagnostic test poses risk to humans
fungal isolation
what are the two tests used in histopathology
- Periodic Acid-Schiff Reaction
- Grocott/Gomori Methenamine Silver
if fungal hyphae are too big, how does the immune system target them?
via pyogranulomatous response
what are the 4 types of fungal diseases
- systemic mycoses
- sq or deep mycoses
- cutaneous mycoses
- mycotoxicoses
describe Histoplasma capsulatum (type, species, spread, evasion mechanism)
type: systemic
species: cats and dogs
spread: via alveolar macrophages to lymph
evasion mechanism: prevents lysis in phagolysosome by enzyme inhibition
describe cryptococcus neoformans (type, species, spread, evasion mechanism)
type: systemic
species: cats, dogs, cattle, horses, humans
spread: from nasopharynx to CNS by direct extension
evasion mechanism: thick capsule
*narrow-based budding
describe aspergillus fumigatus (type, species, spread, etc.)
type: systemic
species: all
spread: inhalation/ingestion/injection spread in macrophages through vessels
evasion mechanism: secrete toxins that slow mucociliary apparatus
describe sporothrix schenckii (type, species, spread, etc.)
type: sq
species: cats, dogs, horses, humans
spread: cutaneolymphatic and local proliferation
evasion: capsules
describe pythium insidisum (type, species, spread, etc.)
type: sq
species: horses, cattle, dogs, cats
*aquatic oocyte
what is the proper treatment for pythium insidiosum
aggressive surgical excision with wide margins
what is also known as “kunkers” in horses
pythium insidiosum
describe dermatophytoses (type, species, spread, etc.)
type: cutaneous
spread: stratum corneum infection, hyphae branches to arthroconidia and infect nearby surfaces
*ringworm
What is Microsporum canis
- 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
mycotoxin
- secondary metabolite of fungus
- disease depends on the individual mycotoxin
- no treatment
describe aflatoxin B1 (type, species, spread, etc.)
type: mycotoxin
spread: ingestion of contaminated feedstuffs and conversion via cytochrome P450
*binds to cellular DNA, RNA, or proteins
describe phomopsins or lupinosis (type, species, effect)
type: mycotoxin
species: cattle, sheep, horses
effect: hepatic dysfunction (lipidosis)
describe amantia (type, species, spread, etc.)
type: mycotoxin (poison mushrooms)
effect: inhibits RNA poly. II, liver necrosis, irreversible disruption of actin
what are the 2 contagious fungi
Microsporum canis and Sporothrix schenckii
