Microbiology - Fungal infections

Question 1

What is the main conponent of fungal cell walls?

Answer 1

Chitin

Question 2

What is the main component of fungal cell membranes?

Answer 2

Ergosterol

Question 3

What is the reproductive method of yeats?

Answer 3

Budding

Question 4

Recall 3 examples of yeasts that are clinically important

Answer 4

Candida
Cryptococcus
Histoplasma (dimorphic)

Question 5

What are moulds?

Answer 5

Multicellular hyphae

Question 6

Give 3 examples of moulds that are clinically important

Answer 6

Dermatophytes
Aspergillus
mucormycetes.

Question 7

what drug to treat Candida albicans

Answer 7

fluconazole

amphetricin B for invasive disease

Question 8

2 principles of candidiasis management

Answer 8

serology for B-D-glucan

antifungals

Question 9

Recall the different types of cryptococcus, and which of these infect immunodeficient vs immunocompetent hosts

Answer 9

Serotypes A and D = cryptococcus neoformans (immunodeficient hosts)

Serotypes B and C = cryptococcus gatti (immunocompetent hosts)

Question 10

Which type of cryptococcus can cause meningitis?

Answer 10

Cryptococcus gatti

Question 11

What ink can be used to stain for cryptococcus?

Answer 11

India Ink (all black apart form distinct capsule around yeast)

Question 12

How should cryptococcus infection be managed?

Answer 12

1. Induction: 2/52 of amphotericin B + flucytosine

2. Consolidation: 8/52 of high dose oral fluconazole

Question 13

Which type of aspergillus disease is an allergic disease?

Answer 13

ABPA - Allergic bronchopulmonary aspergillosis

Question 14

How does aspergillus appear under the microscope?

Answer 14

Fluffy colonies

Question 15

What parts of the body can be infected by aspergillus?

Answer 15

Pre-formed cavities (eg. by TB) - so treated pulmonary TB may be in the history

Question 16

What is a galactomannan assay used for?

Answer 16

Aspergillosis diagnosis

Question 17

Why is pneumocystis jirovecii an unusual fungus?

Answer 17

No ergosterol

Question 18

What is the typical history for PCP pneumonia?

Answer 18

Desaturating on exertion

Question 19

What are the clinical features of mucormycoses?

Answer 19

Orbital/facial cellulitis with discharge of black pus from nose/ palate

Question 20

How are mucormycoses managed?

Answer 20

LONG duration of ambisone (amphotericin B)

Question 21

Recall 2 examples of a dermatophyte

Answer 21

tinea

ringworm

Question 22

Where does tinea cruris infect?

Answer 22

Groin

Question 23

How is tinea diagnosed?

Answer 23

Often clinically, but can be confirmed via skin scrapings for MC&S

Question 24

Recall 4 classes of antifungal

Answer 24

Azoles - membrane
Polyenes - membrane
Echinocandins -inhibit glucan synthase (cell wall)
Pyrimidine analogues - dna synthesis

Question 25

Recall the side effect profile of each class of antifungal

Answer 25

Azoles - abnormal LFTs PolyeNes - Nephrotoxicity Echinocandins - relatively innocuous Pyrimidine analogues - blood disorders

Question 26

What is the mechanism of action of azoles?

Answer 26

Inhibit ergosterol synthesis

Question 27

What is the mechanism of action of polyenes?

Answer 27

Bind sterols in membranes to create leakage of electrolytes

Question 28

Give 2 examples of polyene medications

Answer 28

Amphotericin B | Nystatin

Question 29

Which 2 types of fungus are echinocandins particularly useful for?

Answer 29

Candida | Aspergillus

Question 30

What class of antifungal is flucytosine? mechanism?

Answer 30

Pyrimidine analogue - INHIBITS dna SYNTHESIS

Question 31

what stain for candida

Answer 31

periodic acid schiff (PAS)

Question 32

most common candida

Answer 32

Candida albicans

Question 33

what's the germ tube test? what so you see for what organism

Answer 33

Germ tube test is a screening test for the presumptive identification of Candida albicans only albicans has pseudohyphae

Question 34

what can candida cause in the eyes & in mouth

Answer 34

candida endophthlamitis | angular chelitis

Question 35

what agar to detect candida

Answer 35

sabouraud agar | can also detect w beta-d glutan assay

Question 36

what is the management of candidiasis

Answer 36

eco and fundoscopy if albicans - fluconazole if not - echinocandin

Question 37

Cryptococcus gatti grows in which plant

Answer 37

eucalyptus

Question 38

what crypotocccus is common in those w AIDS

Answer 38

neoformans | 2nd most common cause of death in AIDS

Question 39

cryptococcal meningitis can cause what in the brain

Answer 39

hydrocephalus | in LP CSF isn't mixed w CSF in brain

Question 40

what stain to diagnose aspergillosis

Answer 40

Grocott methenamine silver (GMS)

Question 41

treatment of aspergillosis

Answer 41

amphoetrcin B | not fluconazole for moulds as poor activity

Question 42

what causes pityriasis versicolour

Answer 42

looks like vitiligo | caused by malassezia fur

Question 43

mucormycosis happens in which 2 patients

Answer 43

imunocompromised | poorly controlle diabetics

Question 44

cellulitis of orbit and black pus = what disease

Answer 44

mucormycosis

Question 45

severe brain consequence of mucormycosis

Answer 45

rhinocerebral mucormycosis | murco. is caused by rhizopum and rhizomucor spp

Question 46

management of mucormycosis

Answer 46

ENT referral as surgical emergency | high dose amphotericin B

Question 47

tines pedis, tinea cruris, tinea capatis and onchomycosis (fungal nail) are all caused by?

Answer 47

trichophyton rubrum | many other too but this is common to all

Question 48

which anti fungal works for virtually all fungi

Answer 48

amphotericin B

Question 49

what fungi are resistant to echinocandins

Answer 49

Cryptococcus

Question 50

give an example of an echinocandin

Answer 50

micafungin

Question 51

mechanism of polyenes

Answer 51

bind ergosterol in cell membrane, creating channels

Question 52

mechanism of azoles

Answer 52

inhibit enzyme in cell membrane (lanosterol 14 a demythelyase)

Question 53

mechanism of echinocandins

Answer 53

inhibit beta d glucan synthase