fungi and opportunistic infections

Question 1

are fungi eurkaryotic or prokaryotic

Answer 1

eukaryotic

Question 2

what are the 3 classifications of fungi

Answer 2

unicellular (yeasts)
filamentous (moulds)
dimorphic

Question 3

explain the features of unicellular fungi

Answer 3

• facultative anaerobes
• reproduce asexually by budding
• produce colonies on agar

Question 4

explain the features of filamentous fungi

Answer 4

• aerobes
• reproduce by conidia (asexual spores)
• produce mycelia on agar

Question 5

explain the features of dimorphic fungi

Answer 5

they can switch between unicellular and filamentous forms

Question 6

what is a hypha

Answer 6

a long, multicellular condidium (asexual spores)

Question 7

which type of fungi is more virulent to humans and why

Answer 7

dimorphic fungi - because they can grow as filamentous organisms in the environment and then change to growing as unicellular within us

Question 8

where do dermatophytes live on humans

Answer 8

within keratin layers (hair, skin)

Question 9

give an example of a dermatophyte

Answer 9

tinea corporis = ring worm (not actually a worm!)

Question 10

what are the 3 types of candidiasis infection

Answer 10

• mucocutaneous
• chronic mucocutaneous
• systemic (causes septicaemia)

Question 11

what are 2 diseases caused by cryptococcosis

Answer 11

pulmonary infection

meningitis

Question 12

what is important to remember about crytococcocal meningitis

Answer 12

it is an AIDS defining illness

Question 13

what are the two agents that cause cryptococcosis

Answer 13

C. neoformans

C. gattii

Question 14

what are the 3 types of aspergillosis infection

Answer 14

• saprophytic (fungus ball)
• allergic
• systemic

Question 15

how do you diagnose fungal infections

Answer 15

microscopy
culture 
antigen detection
PCR
mass spectrometry

Question 16

what are the systemic anti-fungal chemotherapy drugs

Answer 16

polyenes (amphotericin B)
triazoles (fluconazole)
echinocandins
5-fluorocytosine

Question 17

what are the topical anti-fungal treatments

Answer 17

polyenes

imidazoles

Question 18

what are the targets of anti-fungal medications

Answer 18

ergosterol in cytoplasmic membrane

nucleic acids

Question 19

which anti-fungal drugs affect the cytoplasmic membrane and how

Answer 19

polyenes affect the integrity

allylamines, trizoles and morpholines affect the synthesis

Question 20

what is the bad thing about using anti-fungals that target the cytoplsamic membrnae of fungi

Answer 20

they also bind to our cholesterol in our membrane

Question 21

which antifungal drug affects the nucleic acids of fungi

Answer 21

5-flurocytosine = converted to 5-flurouracil - affects DNA and RNA synthesis

Question 22

empiric treatment of candida spp

Answer 22

fuconazole (trizaole 1st gen)

Question 23

empiric treatment of cryptococcus

Answer 23

amphotericin B (polyene) + 5-flurocytosine

Question 24

empiric treatment of aspergillus

Answer 24

voriconazole (triazole 2nd gen)

Question 25

empiric treatment of dimorphic fungi

Answer 25

amphotericin B (polyene)

Question 26

which opportunistic bacteria are associated with nosocomial epidemics

Answer 26

- staph aureus - Klebsiella pneumoniae - enterococcus spp - pseudomonas aeruginosa - enterobacter spp - serratia spp

Question 27

what are the local alterations of a patient that allow infection by opportunistic pathogens

Answer 27

- anatomical defect - surgical and other wounds - burns - catherterisation - foreign bodiesin general

Question 28

what are the systemic alterations of a patient that allow infection by opportunistic pathogens

Answer 28

- extremes og age - leucopenia - malignancy - malnutrition - diabetes - liver disease - certain infections (HIV, measles) - treatment with antimicrobials - primary immunodeficiency

Question 29

what are the types of infection that a patient can get with an opportunistic infection

Answer 29

- wound infection - UTI - intra-abdominal infection - pneumonia - septicaemia - meningitis

Question 30

what are the features of pseudomonas

Answer 30

- gram negative rod - motile - aerobes or facultative anaerobes - non-fermenting, non-sporing - catalase and oxidase positive - low nutritional requirements

Question 31

pseudomonas is divided into different species according to...

Answer 31

biochemical tests

Question 32

how is pseudomonas aeruginosa subtyped

Answer 32

serotyping, biotyping

Question 33

which 4 bacteria usually colonise the respiratory tract of patients with CF

Answer 33

psuedomonas aueroginosa burkholderia cepacia stenotrophomonas maltophilia burkholderia pseudomallei

Question 34

which systemic infections is pseudomonas aeruginosa now mostly associated with

Answer 34

penumonia, UTI and sepsis

Question 35

which superficial infections is pseudomonas aeruginosa associated with

Answer 35

skin - wound infection, otitis externa, folliculitis eye - keratitis, corneal ulcer (places where innate immunity is reduced)

Question 36

how does pseudomonas aeruginosa adhere to skin

Answer 36

via flagella, pili and LPS | - LPS and flagellin bind to TLRs -> affect cytokine production

Question 37

why is pseudomonas aeruginosa associated with patients with CF

Answer 37

because it binds to the CFTR and it is not inhibited by high salt concentrations

Question 38

what features of pseudomonas aeruginosa help it to adhere and invade other than flagella and LPS

Answer 38

- once adherent, it tends to produce a biofilm | - it has a capsule - assists adherence and biofilm formation, and makes it resistant to immune system

Question 39

what are the properties of pseudomonas aeruginosa within the biofilm it makes

Answer 39

- non motile - more adherent - more capsule materia - less invasive - slow growth - increased R to AB - shorter LPS

Question 40

what causes the change in properties of pseudomonas aeruginosa when it is in a biofilm

Answer 40

activation of genes that are regulated by quorum sensing

Question 41

what things help pseudomonas aeruginosa spread through the tissues

Answer 41

flagella exoenzymes exotoxins LPS-CFTR mediated nvasion

Question 42

which exoenzymes does pseudomonas aeruginosa have and what do they do

Answer 42

proteases, haemolysins, phospholipases, elastase --> act on pulmonary tissue and surfactant

Question 43

what exotoxins does pseudomonas aeruginosa have and what do they do

Answer 43

exotoxin A, exoenzymes S and U --> inhibit phagocytosis

Question 44

ways to manage pseudomonas aeruginosa in the environment

Answer 44

- reduce risk of susceptible patients - be on alert for infection and treat early - practice high levels of hand hygiene - use contact lenses and solutions appropriately - lifelong monitoring and Tx of CF patients