mycology

Question 1

what are the 3 classifications of fungi

Answer 1

1. yeast
   unicellular eg candida
2. filamentous fungi aka mould
   hairy looking, hyphae are thread like tubes, multicellular eg aspergillus
3. 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

Question 2

how are fungal infections transmitted

Answer 2

no evidence of transmission among humans or animals. environmental, laboratory acquired infection

Question 3

what kind of media is used to culture fungi

Answer 3

sabouraud dextrose agar (contains blood). cultures grow as creamy white colonies

Question 4

what is unique about candida albicans and cindida dubliniensis

Answer 4

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)

Question 5

how is candida albicans treated

Answer 5

azoles (block demethylation of lanosterol to ergosterol to inhibit growth)

Question 6

if germ tube test and cornmeal agar test for candida came back negative, how to treat

Answer 6

not c albicans. treat with nyastatin (polyene, form pores by binding ergosterol)

Question 7

do fungi possess exo and endo toxins

Answer 7

no, except for aspergillus hence slow chronic infection rather than acute disease

Question 8

risk factors for oral candidiasis

Answer 8

prior exposure to antibiotics, immunological and endocrine disorders eg diabetes, immunocompromised, radiation to head and neck

Question 9

what are the 3 clinical manifestations of oral candidiasis

Answer 9

1. pseudomembranous
2. erythematous
3. hyperplastic

Question 10

what are the clinical features of pseudomembranous oral candidiasis

Answer 10

white membranes on surface of oral mucosa and teeth, plaque resembling milk curds. can wipe off to resemble raw erythematous bleeding base

Question 11

which patients susceptible to pseudomembranous oral candidiasis

Answer 11

acute infection in patients using corticosteroids, hiv, neonates, terminally ill ie IMMUNOCOMPROMISED

Question 12

how to treat pseudomembranous oral candidiasis

Answer 12

topical antifungals: polyenes eg nystatin and amphotericin given as logenzes or pastilles

Question 13

how does erythematous oral candidiasis arise

Answer 13

due to persistent pseudomembranous oral candidiasis (when pseudomembrane is shed). frequently observes in denture wearing people

Question 14

how to treat erythematous and hyperplastic oral candidiasis

Answer 14

topical antifungal mainly nystatin and amphotericin

azole group agents in patients with HIV

Question 15

what are the causes of hyperplastic oral candidiasis

Answer 15

associated with oral cancer

Question 16

how does hyperplastic oral candidiasis manifest clinically

Answer 16

discrete raised areas (can be small palpable translucent areas or large dense opaque areas)

plaque like lesions that are hard and rough to touch

Question 17

how to test hyperplastic oral candidiasis and how does it differ from other 2 variants

Answer 17

biopsy vs swabs for other two variants. biopsy to rule out malignancy

Question 18

what are some candida associated lesions

Answer 18

angular stomatitis/cheilitis, linear gingival erythema, median rhomboid glossitis (papillary trophy at midline of tongue)

Question 19

what causes cheilitis

Answer 19

yeast, staph aureus (presence of yellow crusting), isolated initial sign of anemia or vitamin deficiency

Question 20

how to treat fungal cheilitis

Answer 20

nyastatin, amphotericin B, miconazole which has both antifungal and antistaphylococcal properties

Question 21

how to treat mycoses

Answer 21

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

Question 22

what is cryptococcus

Answer 22

type of yeast

Question 23

what does cryptococcus cause

Answer 23

meningitis

oral ulcerations commonly amongst immunocompromised patients

Question 24

what type of fungus uniquely has urease activity and phenole oxidase

Answer 24

cryptococcus

Question 25

where is cryptococcus found in the environment

Answer 25

bird droppings

Question 26

how to visualise cryptococcus

Answer 26

india ink staining to highlight huge capsule

Question 27

what are dermatophytes

Answer 27

mould that infects skin, hair, nails (superficial infections)

Question 28

what kind of fungus is aspergillosis

Answer 28

filamentous fungi, mould

Question 29

is aspergillosis primary or secondary pathogen

Answer 29

found in air especially dusty environment, harmless to normal people

opportunistic disease in immunocompromised ie secondary

colonises at sinus and lungs

Question 30

which fungi pushes lid of agar plate when being cultures

Answer 30

zygomyces

Question 31

what fungi causes rhinocerebral mucomycosis in diabetic patients (requires aggressive surgery to remove)

Answer 31

zygomyces

Question 32

which fungus when grown on culture appears cottony, greyish in colour

Answer 32

aspergillus fumigatus

Question 33

which fungus when grown on culture appears yellow green in colour

Answer 33

Aspergillus flavus

Question 34

what is wet mount for fungi stained with

Answer 34

lactophenol cotton blue:

phenol kills live organisms. lactic acid preserves fungal cultures. cotton blue preserves chitin in fungal cell walls