Mycology

what is mycology?

study of fungi

where is fungi found?

environment - decaying vegetation, moldy hay

skin and mucous membranes - host adapted or contaminants from enrivonment

what are the major characteristics of fungi?

eukaryotes, majority saprophytes and non-pathogens

how do fungi reproduce?

asexually by fragmentation, budding and through spores; sexual reproduction is also seen

what do fungi cell membranes contain?

sterols (ergosterol)

true/false - fungi contain a cell wall

true; contains glucan, mannan, chitin

what are the unicellular forms of fungi called?

yeast

what are the multicellular fungi called?

mold

what does mold contain to spread?

hyphae and fruiting bodies which contain spores

what are a tangled group of hyphae called?

mycelium

what is the colonial morphology of yeast?

opaque, creamy, smooth

what is the microscopic morphology of yeast?

unicellular forms round single cells, budding

what is the colonial morphology of molds?

wooly-fluffy-powdery colonies, aerial growth

what is the microscopic morphology of molds?

hyphae

what is the colonial morphology of dimorphic fungi?

combination of yeast and mold depending on temperature

what is the microscopic morphology of dimorphic fungi?

yeast or hyphal, depending on temperature

what is used to differentiate between fungi organisms?

hyphae divided based on presence of septa

what is the general pathogenesis of fungal infections?

fungus invade tissue and induce pathogenic effect; environment/opportunistic organisms infect mainly immunocompromised hosts; fungal infection results in induce chronic granulomatous infection; infections uncommon, but serious; limited antimicrobial agents

what is mycotoxicosis?

fungal contamination or growth on food material leads accumulation of toxins and when consumed induce severe disease

how does fungi impact allergies?

inhaled fungal spores induce hypersensitivity and allergy

where is this fungal infection?

superficial - outermost layers of the skin and hair

where is the fungal infection?

cutaneous - extend deeper into the epidermis, invasive hair and nail

where is the fungal infection?

subcutaneous - dermis, SQ, muscle and fascia

where is the fungal infection?

systemic - primarily in lung, spreads to other organs

how are fungal infections diagnosed?

morphology recognition - cytology, histopathology, went mounts

detection of fungal components - Beta D-glucan assay

detection of host immune response - antibodies, agar gel, ELISA

culture and ID

PCR

what is the stain used on fresh tissue to detect fungi?

calcofluor stain - binds to chitin in cell wall; requires UV microscope

what are the 3 agars used to culture fungi?

sabouraud dextrose agar, sabouraud dextrose agar with cycloheximide, dermatophyte test media

what is used to definitive id fungi?

by DNA probes/sequencing, serotyping, mating studies, virulence testing

when are beta-d glucan assay performed?

general screening of invasive fungal disease

what species of fungi is diagnosed by latex agglutination test or lateral flow tests?

cryptococcus neoformans - in cats

what is a great tool used to detect antigen from fungal infection?

fungal serology-A

what are the 5 examples of antifungal drugs?

polyenes (amphotericin B, natamycin, nystatin)

flucytosine

azoles

allylamines

griseofulvin

how do polyenes, azoles, allylamines work?

inhibit ergosterol

how do flucytosines work?

inhibit nucleic acid synthesis

how do griseofulvin work?

binds to mitotic spindles, inhibits mitosis; administered orally, accumulates in skin

why are antibodies usually not protective in fungal infections?

immunity against fungal infections are usually cell-mediated; most lesions are granulomatous