Fungus

Question 1

Which fungi must be handled in BSL-III?

Answer 1

histoplasma, blastomyces, coccidioides

Question 2

What aspergillus spp is resistant to amphotericin B and has decreased sensitivity to voriconazole?

Answer 2

Aspergillus terreus

Question 3

Which aspergillus spp has alfatoxin and what does aflaxotin do?

Answer 3

Aspergillus flavus

carcinogenic hepatotoxin

Question 4

Which species of aspergillus has aleuriocondia

Answer 4

Aspergillus terreus

Question 5

Which dimorphic fungi produces spherules in tissue section?

Answer 5

coccidioides immits

Question 6

Which candida species is resistant to fluconazole?

Answer 6

Candida glabrata

Candida krusei

Question 7

Amphotericin belongs to which class of antifungals and what is the MOA?

Answer 7

class: polyenes
MOA: bind ergosterol in the cell membrane and alter the selective permeablility of the membrane

Question 8

What are the clinical indications for amphotericin?

Answer 8

Candida
Geotrichum
Cryptococcus
Mucormycosis
Aspergillosis (invasive)
Dimorphic fungi (severe infection)

Question 9

Name the azoles and their MOA

Answer 9

fluconazole, posaconazole, itraconazole, voriconazole, isavuconazole
MOA: interfere with synthesis of ergosterol and disrupt the integrity of the cell membrane

Question 10

What are the clinical indications for fluconazole

Answer 10

candida

cryptococcus

Question 11

clinical indications voriconazole

Answer 11

candida (fluconazole resistant)
aspergillus
fusarium

Question 12

clinical indications itraconazole

Answer 12

cryptococcus
aspergillus
dimorphic fungi (mild-mod infections)
onychomycosis

Question 13

clinical indications posaconazole

Answer 13

candida
aspergillus
mucormycosis

Question 14

Organisms resistant to amphotericin

Answer 14

trichosporon
aspergillus terrues
fusarium (inc MIC)

Question 15

organisms to azoles (general)

Answer 15

rhodotorula
mucomycosis (except posaconazole)

Question 16

organisms resistant to fluconazole

Answer 16

C. glabrata
C. krusei
Geotrichum capitatum
fusarium

Question 17

organism resistant to voriconazole

Answer 17

Aspergillus terreus

Question 18

Echinocandins and MOA

Answer 18

caspofungin, micafungin, anidulofungin

MOA: inhibit 1,3-beta-glucan synthesis (involved in cell wall synthesis)

Question 19

Clinical indications echinocandins

Answer 19

Candida incl. krusei and glabrata (fungicidal)

Aspergillus (fungistatic)

Question 20

organisms resistant to echinocandins

Answer 20

C. parapsilosis
Geotricum capitatum
Cryptococcus neoformans
Trichosporon
Rhodotorula
mucormycosis
fusarium

Question 21

5-flucytosine MOA

Answer 21

fluorinated pyrimidine base is metabolized to 5-FU, incorporated into fungal RNA and inhibits protein synthesis

Question 22

clinical indications 5-Flucytosine

Answer 22

Candida

cryptococcus

Question 23

organisms resistant to 5-flucytosine

Answer 23

malassezia
trichosporon
mucormycosis

Question 24

Terbinafine MOA

Answer 24

inhibit ergosterol synthesis by inhibiting squalene epoxidase

Question 25

clinical indications terbinafine

Answer 25

dermatophytes | useful in combination therapy for resistant fungi

Question 26

Griseofulvin MOA and clinical indications

Answer 26

binds microtubule proteins, inhibiting mitosis | used for dermatophytes which are unresponsive to azoles

Question 27

What does cryptococcal antigen test for?

Answer 27

capsular polysaccharide

Question 28

What is galatcomannan useful for?

Answer 28

detecting aspergillus infection | galactomannan is component of aspergillus cell wall

Question 29

What is 1,3-beta-d-glucan useful for?

Answer 29

any invasive fungal infection | polysaccharide component of most fungi cell wall

Question 30

What is chitin?

Answer 30

component of cell wall composed of n-acetyl glucosamine

Question 31

What is ergosterol?

Answer 31

forms cell wall. Target of many antifungals

Question 32

what is the germ tube test? which fungi will show positive germ tube test?

Answer 32

Early formation of true hyphae at 37°C; takes 2-3 hours | Positive reaction with Candida albicans/dubliniensis

Question 33

Which phyla will show a positive urease test?

Answer 33

Basidiomycetes will be positive vs ascomycetes negative. Basidiomyctes include cryptococcus, malassezia, trichosporon, rhodutorula. Ascomycetes include Candida spp and Geotrichum spp

Question 34

Which two fungal spp can be identified on PNA FISH from pos blood cx?

Answer 34

Candida albicans and Candida glabrata

Question 35

Chromagar green

Answer 35

C. albicans/dubliensis PNA fish green germ tube pos

Question 36

Chromagar pink

Answer 36

C. glabrata "dirty pink",PNA FISH red budding yeast with no pseudohyphage Vs C. krusei: pseudohyphae with elongated blastoconidia

Question 37

Chomagar blue

Answer 37

C. tropicalis

Question 38

Chromagar white/pink

Answer 38

C. parapsilosis

Question 39

Which Candida spp are resistant to fluconazole

Answer 39

C. glabrata and C. krusei

Question 40

cryptococcus neoformans is resistant to which class of antifungals

Answer 40

echinocandins

Question 41

Which organism causes tinea versicolor and how is it treated?

Answer 41

Malassezia clusters of round budding yeast-like cells and short hyphal forms; “spaghetti and meatballs” Urease (+) Tx: 5-Flucytosine

Question 42

Which drug is treatment of choice for mucorales?

Answer 42

amphotericin B | resistance to azoles, echinocandins and 5-flucytosine

Question 43

What is treatment for dimorphic fungi?

Answer 43

fluconazole or itraconazole (mild) | amphotericin (severe)