fungi

Question 1

give two situations in which fungal infections are common?

Answer 1

after abdominal surgery

in the immunocompromised

Question 2

what are fungi?

Answer 2

eukaryotic
Chitinous cell wall
Heterotrophic
“Move” by means of growth or through spores, which are carried through air or water

Question 3

name two types of fungi and which is a more common cause of infection?

Answer 3

mould and yeast and mould is much more common

Question 4

what is the difference between yeast and mould?

Answer 4

yeast - single celled, divide by budding

mould - multicellular hyphae, form spores

Question 5

what are diamorphic fungi?

Answer 5

they can be yeasts or moulds depending on the conditions

Question 6

give examples of clinical diseases caused by fungal infection

Answer 6

Nappy rash and Vulvovaginal candidiasis
Tinea pedis (athlete’s foot)
Onychomycosis (fungal nail infections)
Otitis externa
Fungal asthma
tinea capitis and fungal keratitis

Question 7

name a special agar plate used for fungi

Answer 7

Sabouraud agar

Question 8

what stain used in histology can be used to detect fungi?

Answer 8

silver stain

Question 9

name infections that can be life threatening in immunocompromised people

Answer 9

Candida line infections
Invasive aspergillosis
Pneumocystis
Cryptococcosis
Mucormycosis

Question 10

why is so much money spent on antifungals?

Answer 10

diagnosis is poor so people may be give anti-fungals just in case
new drugs so are expensive

Question 11

what is selective toxicity?

Answer 11

achieve inhibitory levels of agent at the site of infection without host cell toxicity

Question 12

why is selective toxicity difficult for fungi?

Answer 12

as they are eukaryotic

Question 13

which antifungal targets DNA/RNA synthesis, protein synthesis?

Answer 13

Flucytosine

Question 14

which antifungal targets the cell wall?

Answer 14

Echinocandins

Question 15

which antifungals target the ergosterol plasma membrane?

Answer 15

Amphotericin
Azoles
Terbinafine

Question 16

how does amphotericin B bring about fungal death - fungicidal?

Answer 16

insets pore into the cell membrane and cases leakage of electrolytes and also displaces and affects activity of membrane bound proteins

Question 17

what are the side effects of polyenes?

Answer 17

nephrotoxicity
hypokalaemia
hyperkalaemia
chills/rigors. hypotension 
anaphylaxis

Question 18

how do azoles and terbinafine work?

Answer 18

they inhibit the ergosterol pathway

Question 19

what are the advantages of terbinafine?

Answer 19

well absorbed and distributes extensively to poorly perfused tissues
works for candida and aspergillus

Question 20

what are the drawbacks of terbinafine?

Answer 20

metabolised by CYP450 enzymes so can result in drug interactions
extensive first pass metabolism

Question 21

is terbinafine fungistatic or fungicidal?

Answer 21

fungicidal

Question 22

are azoles fungistatic or fungicidal?

Answer 22

fungistatic

Question 23

what are the advantages of triazoles?

Answer 23

improve and broadened antifungal spectrum

Question 24

what are the adverse effects of azoles?

Answer 24

hepatitis
Alopecia - fluconazole
GI symptoms- Itra:
Nausea, abdominal pain, diarrhoea
Rare life threatening liver failure - itra
Voriconazole - visual disturbance in 30%
Photosensitivity in 1-2% voriconazole and skin malignancy

Question 25

list some drugs that interact with fluconazole

Answer 25

Warfarin, phenytoin, calcineurin inhibitors, anxiolytics

Question 26

list drugs that interact with itraconazole or voriconazole

Answer 26

Warfarin, phenytoin, calcineurin inhibitors, anxiolytics, steroids, statins, rifamycins,PIs

Question 27

list 3 ways in which azoles can become resistant

Answer 27

target site modification by mutation increased expression of a gene efflux pumps that pump out the azole

Question 28

what is the first line azole?

Answer 28

fluconazole

Question 29

which enzyme do echinocandins inhibit?

Answer 29

1,3 beta glucan synthase

Question 30

what are echinocandins good for?

Answer 30

reisitant candida and mould infections

Question 31

what method of administration are echinocandins given in?

Answer 31

IV, as poor oral bioavailability

Question 32

where are areas of poor penetration of Echinocandins?

Answer 32

CSF, eye and urine

Question 33

what are some side effects of Echinocandins

Answer 33

Rare type-1 hypersensitivity Hepatotoxicity Hypokalaemia

Question 34

what is the most common species of candida to infect a central line?

Answer 34

C. albicans

Question 35

what is the most common cause of fungal nails?

Answer 35

mould - Trichophyton rubrum

Question 36

what substance is released into the serum by the fungi during invasive infection that can be measured?

Answer 36

1,3 beta D glucan

Question 37

in which pts is Pneumocystis most common?

Answer 37

HIV, transplant, steroids

Question 38

what is the first line therapy for PCP (pneumocystis pneumonia)?

Answer 38

Co-trimoxazole