fungal infections

Question 1

biology of fungi

Answer 1

eukaryotic
chitinous cell wall
heterotrophic

Question 2

how do fungi move

Answer 2

by means of growth or through the generation of spores which are carried through air or water

Question 3

what is yeast

Answer 3

yeasts are small single called organisms that divide by budding

Question 4

what % of fungal species are yeast

Answer 4

yeast account for <1% of fungal species

Question 5

describe moulds

Answer 5

moulds form multicellular hyphae and spores

some fungi exist as both yeasts and mould switching between the two when conditions suit - dimorphic fungi

Question 6

how many species of fungi are there

Answer 6

5 million

but only a few hundred have been reported as causing human infection

Question 7

why do only a few hundred fungi affects humans

Answer 7

because they are unable to grow at 37 degrees

and because of the innate and adaptive immune response

Question 8

are there lots of anti fungal drugs

Answer 8

no there are limited options

Question 9

describe dna/rna synthesis of fungi

Answer 9

its similar to mammalian

via protein synthesis

Question 10

describe fungal cel wall

Answer 10

mannoproteins
B1,3 glucan
B1,6 glucan
chitin

doesn’t exist in humans

Question 11

describe fugal cell membrane

Answer 11

contains ergosterol

human cell membrane contains cholesterol not ergosterol

Question 12

what drugs affect dna synthesis in fungi

Answer 12

flucytosine

griseofulvin

Question 13

which drugs affect fungal cell wall

Answer 13

echinocandins

Question 14

which drugs affect plasma membrane of fungi

Answer 14

polyenes eg amphotericin
azores
allylamines eg terbinafine

Question 15

which fungal ifnection is very common

Answer 15

superficial fungal infection

Question 16

which fungal ifnection is rare

Answer 16

invasive fungal infection

it’s rare but its easily missed

Question 17

are life threatenig fungal infections common

Answer 17

no
life threatening fungal infection is rare in healthy hosts

but most people would have had normal fungal infections

Question 18

what are dimorphic fungi

Answer 18

Some fungi exist as both yeasts and moulds switching between the two when conditions suit

Question 19

what is mucosal candidiasis

Answer 19

a common and recurrent disease that causes significant morbidity

Question 20

risk factors for mucosal candidiasis

Answer 20

immunosuppresion
diabetes
antibacterial therapy
mucosal disruption

Question 21

treatment for mucosal candidiasis

Answer 21

topical or oral azoles

Question 22

impact of resistance on mucosal candidiasis

Answer 22

resistant disease is common in recurrent cases

acquired resistance in normally susceptible species

selection for intrinsically resistant species

Question 23

what are dermatophyte infections due to

Answer 23

trichophyton spp
microsporum spp
epidermophyton floccosum

Question 24

how can you get dermatophyte infections

Answer 24

human-human or animal-human transmittion

Question 25

treatment for dermatophyte infections

Answer 25

usually with topical or oral azoles or terbinafine

Question 26

examples of dermatophyte diseases

Answer 26

tines capitis tines corporis tinea cruris tinea unguium tinea pedis

Question 27

is ringworm a worm

Answer 27

no

Question 28

how do dimorphic fungi cause disease

Answer 28

they can cause severe infection in healthy hosts in endemic areas infection via inhalation of conidia from soil or implantation

Question 29

what temp do dimorphic fungi mould at

Answer 29

ambient temp 25-30 C

Question 30

when do dimorphic fungi convert to yeast form

Answer 30

at 37C occurs in response to heat related stress on organism

Question 31

what does ‘true pathogens’ refer to

Answer 31

infect healthy hosts

Question 32

what diseases can coccidioides cause

Answer 32

asymptomatic/ sub clinical ifne3ction is common most of rest - community acquired pneumonia severe disease - respiratory failiure or septic shock late disease - does not correlate with severity of initial smtooms

Question 33

late manifestations of coccidioides

Answer 33

cavitatory lung disease orthopaedic cutaneous ulcers and abscesses cervical lymphadenopathy intracranial - chronic meningitis s

Question 34

describe NHS anti fungal spend

Answer 34

>£150m/year much of this cost is prophylaxis or empirical treatment of possible invasive fungal disease due to poor diagnostics

Question 35

what does fungal diagnosis usually rely on

Answer 35

relies on it being in the differential

Question 36

what is invasive candidiasis

Answer 36

a disease that is mostly due to ifnection of prosthetic devices or intra and abdominal disease

Question 37

what does cryptococcus cause

Answer 37

acute or chronic meningitis in patients with reduced cell mediated immunity

Question 38

differential diagnosis of sub/acute chronic meningitis

Answer 38

• Infective – Tuberculosis – Cryptococcus – Dimorphic fungi – Histoplasma, Coccidioides, Blastomyces – Lyme – Brucella – Syphilis • Non-infective – Sarcoidosis – Behçets’s – SLE – Malignant – Drug induced

Question 39

treatment for cryptococcus

Answer 39

liposomal amphotericin B and flucytosine with maintenance fluconazole

Question 40

are mucorarecous moulds common

Answer 40

no they are rare but cause rapidly progressive infections that cross tissue planets

Question 41

what is the aim of anti microbial drug therapy

Answer 41

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

Question 42

what does antimicrobial drug therapy rely on

Answer 42

upon identifying molecules with selective toxicity for organism targets

Question 43

what are organism targets for antimicrobial drug therapy

Answer 43

Target does not exist in humans Target is significantly different to human analogue Drug is concentrated in organism cell with respect to humans Increased permeability to compound Modification of compound in organism or human cellular environment Human cells are ‘rescued’ from toxicity by alternative metabolic pathways

Question 44

is severe fungal disease commo in healthy people

Answer 44

no Severe disease is caused by a small number of fungi in the immunocompromised Fungal infection can be the initial presentation of the underlying disease

Question 45

why are fungi difficult to treat

Answer 45

because we have relatively few classes of agent effective against them