medical mycology Flashcards
what are mycotoxins?
toxic chemical compounds produced by certain fungi that grow on food crops and other organics
what can spores trigger?
asthma, allergies, occupational diseases (form the fungal infections)
infections
how many people are affected by fungal disease?
over 1 billion but because it’s not as virulent (doesn’t display many symptoms) so it often goes undetected
—— MOST FUNGI HAVE LOW VIRULENCE!
—— DIFFICULT TO DIAGNOSE (indeterminate symptoms)
how can fungal infections be classified? describe them
site of infection
—- superficial: may not illicit an immune response
—- cutaneous: into the epidermis and dermal layer
—- subcutaneous: even deeper, generally requires a wound – could self clear with competent immune system
—- systemic: penetrating the bloodstream and could colonize tissues
route of acquisition
—- exogenous: coming from external source (e.g. breathing in)
—- endogenous: coming from in us – usually occurs when immunocompromised
type of virulence
—- primary mycoses: affects healthy individuals
—- opportunistic mycoses: typically affects immunocompromised individuals
what are dermatophytic fungi? what do they cause? how can it be treated?
dermatophytes cause most superficial/cutaneous mycoses
— infections are usually self-limiting and will clear itself without cellular immune response
causes athlete’s foot and ringworm
can be treated relatively easily using topical antifungal drugs OR oral drugs if severe
what are the common molds for dermatophyte infections
caused by molds from the genera trichophyton, microsporum, and epidermophyton
what are the most common opportunistic fungal pathogens?
yeast species belonging to the genus candida and molds belonging to the genus aspergillus
what type of pathogen is candidiasis?
epithelial surface
most common species is candida albicans
infections
—- oropharyngeal candidiasis (strawberry tongue)
—- denture stromatis
—- vulvovaginal candidiasis
—- chronic mucocutaneous candidiasis
what are the virulence factors of candida?
adhesions
— binds to extracellular matrix or host cells, etc.
dimorphism
— switches between budding stage and hyphael stage to cause invasive infections
phenotypic switching
— changes genetic expression to suit environment
extracellular hydrolases
— can release ^^ to break down things
briefly describe the process of invasive candidiasis
adhesion and colonization
hyphael penetration and invasion
vascular dissemination
how can candidiasis be diagnosed?
selective media culture
detection of anti-candida antibodies and candida antigens in blood sample
describe aspergillosis and what is the one the most commonly infects humans
filamentous fungi, saprophytic
most frequent source of human infection is the aspergillus fumigatus
— it’s geographically restricted to certain areas, depending on where the species can live
what are the virulence factors of aspergillus?
its conidia are dispersed very easily in the air and are routinely inhaled by humans
in immunocompetent individuals, conidia are detected and destroyed by alveolar macrophages
but in immunocompromised individuals, spores can settle, germinate, invade, leading to invasive aspergillosis
virulence factors:
—- thermal tolerance
—- proteinase production: breaks down proteins
—- gliotoxin production: toxic to our cells
—- environmental stress resistance
what’s the mortality rate of aspergillosis?
more than 50%
how is aspergillosis diagnosed?
histopathological analysis
culture of biopsy
bronchoalveolar lavage fluid
