mycology Flashcards
what are the 3 classifications of fungi
- yeast
unicellular eg candida - filamentous fungi aka mould
hairy looking, hyphae are thread like tubes, multicellular eg aspergillus - dimorphic fungi
can exist as either yeast or hairy form. thermally dimorphic; at human body temperature exist as yeast at lower temperatures exist as hairy form
how are fungal infections transmitted
no evidence of transmission among humans or animals. environmental, laboratory acquired infection
what kind of media is used to culture fungi
sabouraud dextrose agar (contains blood). cultures grow as creamy white colonies
what is unique about candida albicans and cindida dubliniensis
they are the only candida species that can produce germ tubes (hyphae) and chlamydospores (germ tube test for hyphae and incubation on cornmeal agar with decreased oxygen to confirm presence for chlamydospores)
how is candida albicans treated
azoles (block demethylation of lanosterol to ergosterol to inhibit growth)
if germ tube test and cornmeal agar test for candida came back negative, how to treat
not c albicans. treat with nyastatin (polyene, form pores by binding ergosterol)
do fungi possess exo and endo toxins
no, except for aspergillus hence slow chronic infection rather than acute disease
risk factors for oral candidiasis
prior exposure to antibiotics, immunological and endocrine disorders eg diabetes, immunocompromised, radiation to head and neck
what are the 3 clinical manifestations of oral candidiasis
- pseudomembranous
- erythematous
- hyperplastic
what are the clinical features of pseudomembranous oral candidiasis
white membranes on surface of oral mucosa and teeth, plaque resembling milk curds. can wipe off to resemble raw erythematous bleeding base
which patients susceptible to pseudomembranous oral candidiasis
acute infection in patients using corticosteroids, hiv, neonates, terminally ill ie IMMUNOCOMPROMISED
how to treat pseudomembranous oral candidiasis
topical antifungals: polyenes eg nystatin and amphotericin given as logenzes or pastilles
how does erythematous oral candidiasis arise
due to persistent pseudomembranous oral candidiasis (when pseudomembrane is shed). frequently observes in denture wearing people
how to treat erythematous and hyperplastic oral candidiasis
topical antifungal mainly nystatin and amphotericin
azole group agents in patients with HIV
what are the causes of hyperplastic oral candidiasis
associated with oral cancer
how does hyperplastic oral candidiasis manifest clinically
discrete raised areas (can be small palpable translucent areas or large dense opaque areas)
plaque like lesions that are hard and rough to touch
how to test hyperplastic oral candidiasis and how does it differ from other 2 variants
biopsy vs swabs for other two variants. biopsy to rule out malignancy
what are some candida associated lesions
angular stomatitis/cheilitis, linear gingival erythema, median rhomboid glossitis (papillary trophy at midline of tongue)
what causes cheilitis
yeast, staph aureus (presence of yellow crusting), isolated initial sign of anemia or vitamin deficiency
how to treat fungal cheilitis
nyastatin, amphotericin B, miconazole which has both antifungal and antistaphylococcal properties
how to treat mycoses
nyastatin, imidazoles for superficial infections
intravenous amphotericin or azoles (not iv because toxic) for systemic infections
fluconazole can be used for both systemic and superficial mycoses
what is cryptococcus
type of yeast
what does cryptococcus cause
meningitis
oral ulcerations commonly amongst immunocompromised patients
what type of fungus uniquely has urease activity and phenole oxidase
cryptococcus
