Microbiology 8s - Fungal infections

Question 1

name 3 yeasts

Answer 1

Candida
Cryptococcus
Histoplasma (dimorphic i.e. can change between yeast and mould)

Question 2

name 2 moulds

Answer 2

aspergillus

dermatophytes

Question 3

stain for candida

Answer 3

periodic acid schiff stain (PAS)

Question 4

why are patients in ITU prone to candida infections?

Answer 4

lots of lines and candida is good at forming biofilms and colonising prosthetics

Question 5

pseudohyphae/germ tube = ?

Answer 5

Candida albicans, no other type of candida infection has this

Question 6

organs infected in systemic candidiasis

Answer 6

spleen + liver

Question 7

culture medium used in candida

Answer 7

Sabouraud agar - contains antibiotics so kills bacteria which compete with candida

Question 8

serology done for candida

Answer 8

beta-D-glucan assay

Question 9

empirical candida management and albicans management

Answer 9

empirical = echinocandins 
fluconazole = albicans specific

Question 10

what drug is cryptoccosu resistant to?

Answer 10

Echinocandins

Question 11

management of crypto coccus

Answer 11

3 weeks amphotericin B +/- flucytosine

Question 12

where does crypto coccus have a predilection for?

Answer 12

CNS

Question 13

WHICH species of cyrptococcus seen in immunocompetent people?

Answer 13

Cryptococcus (neoforamns var) gattii (grows in eucalyptus)

Question 14

diagnostic tests for Cryptococcus

Answer 14

EIA /antigen test, india ink staining

Question 15

diagnosis of aspergillus

Answer 15

microscopy and looking at the SPORES (not hyphae) to identify the species

Question 16

stain used for aspergillus

Answer 16

methenamien silver

Question 17

management of aspergillus

Answer 17

1st line = >6weeks of amphotericin B/ambisome and 2nd line = voriconazole

Question 18

main etiological agent of tinea pedis and tinea cruris + tinea capitis

Answer 18

tricophyton rubrum

Question 19

malassezia furfural –> ?

Answer 19

Pityriasis versicolor

Question 20

antifungals which target the cell membrane

Answer 20

Polyenes e.g. amphotericin B, nystatin and azoles

Question 21

echinocandins e.g. caspofungin MOA

Answer 21

Inhibit cell wall synthesis

Question 22

anti fungals which target DNA/RNA synthesis

Answer 22

Flucytosine

Question 23

azoles MOA

Answer 23

Inhibit ergosterol production

Question 24

voriconazole useful against which fungi?

Answer 24

Aspergillus

Question 25

which azole good for dermatophytes?

Answer 25

Itraconazole

Question 26

amphotericin B vs ambisome

Answer 26

ambisome = amphotericin B + phospholipid layer –> more lipophilic so can enter CNS

Question 27

MOA of polyene antifungals e.g. amphotericin B

Answer 27

bind ergosterol and create transmembrane channels in cell membrane

Question 28

main SE of polyenes

Answer 28

Nephrotoxicity

Question 29

flucytosine MOA

Answer 29

Inhibits DNA synthesis in fungal cells

Question 30

is flucytosine ever given as mono therapy?

Answer 30

No, resistance is becoming a problem so usually given in combination with fluconazole or amphotericin B

Question 31

echinocandins MOA

Answer 31

E..g caspofungin

They work on the cell wall by inhibiting Beta-D-glucan synthase–> osmotic fragility