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Immunology > L4 Antimicrobial > Flashcards

L4 Antimicrobial Flashcards

1
Q

bacterias ribosomes _____ compared to human ribosomes that are ______

A

(30S + 50S) = 70S; 80S

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2
Q

classes of protein synthesis inhibitors that affect the 30S

A
  1. aminoglycosides 2. tetracyclines
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3
Q

classes of protein synthesis inhibitors that affect the 50S

A
  1. chloramphenicol 2. macrolides 3. lincosamides 4. streptogramins 5. oxazolidinones
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4
Q

aminoglycosides are generally bactericidal/bacteriostatic/both

A

bactericidal

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5
Q

aminoglycosides are generally used againist gram + /gram -

A

mainly used against gram -

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6
Q

subclasses of aminoglycosides

A

subclasses: 1. streptomycin 2. gentamicin

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7
Q

anaerobes/aerobes are resistant to aminoglycoside

A

anaerobes are intrinsically resistant

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8
Q

resistance to aminoglycosides

A
  1. alter drug target- methylation of rRNA, mutation of ribosomal protein 2. alter drug exposure- increased efflux, decreased uptake 3. enzymatically inactivate drug- modifications by phosphorylation, methylation adenylation
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9
Q

enzymes are usually encoded on mobile/stationary genetic elements

A

mobile

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10
Q

combinational therapy

A
  • prevent the emergence of resistance - treatment of emergency cases when etiology is still unknown - take advantage of combinational synergy
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11
Q

B lactam and aminoglycoside combinational therapy

A

can be sueful becuase aminoglycoside is large and B lactam can puncture cell wall so large aminoglycoside can enter to target 30S

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12
Q

tetracyclines bind to 30S/50S

A

30S

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13
Q

mycoplasma

A

do not have anything outside of cell membrane, do not have peptidoglycan

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14
Q

B lactams would not be affective againist mycoplasm becuase

A

they do not have petidoglycan cell wall

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15
Q

tetracyclines are generally bactericidal/bacteriostatic/both

A

bacteriostatic

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16
Q

Subclasses of tetracyclines

A

tetracycline and doxycycline

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17
Q

Tetracyclines attack

A

G+, G-, mycoplasma, and intracellular bacteria

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18
Q

Which antibiotic would you use to kill intracellular bacteria?

A

Tetracyclines

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19
Q

tetracycylin is selective for bacteria vs. host cells due to greater uptake in

A

bacteria

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20
Q

_______ and _______ inhibit the absorptions of tetracyclines

A

divalent cations (Ca2+ and Mg2+) so avoid anti-acids and milk

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21
Q

contraindications of tetracycline

A

pregnancy and young children due to inhibition of bone growth and discoloration in teeth

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22
Q

T/F Bacteriostatic and bactericidal agents are not usually combined.

A

true

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23
Q

resistance to tetracyclines

A
  1. alter drug exposure- efflux pumps 2. alter drug target- ribosome protection proteins (prevent drug from binding to the ribosome)
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24
Q

chloramphenicols are generally bactericidal/bacteriostatic/both

A

bacteriostatic but cidial against encapsulated organisms

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25
Q

chloramphenicol bind to 30S/50S

A

50 S

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26
Q

resistance to chloramphenicol

A

enzymatically inactivate drug (modified by acetyl transferases)

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27
Q

macrolides are generally bactericidal/bacteriostatic/both

A

bacteriostatic

28
Q

macrolides bind to 30S/50S

A

50S

29
Q

macrolides subclasses

A

erythromycin and azithromycin

30
Q

macrolides usually work against Gram+ / Gram - with the exception of

A

gram + ; chlamydia

31
Q

lincosamides bind to 30S/50S

A

50S

32
Q

lincosamides are generally bactericidal/bacteriostatic/both

A

bacteriostatic

33
Q

subclass of lincosamide

A

clindamycin

34
Q

lincosamide is highly associated with

A

C difficile

35
Q

streptogramins A and B lincosamides are generally bactericidal/bacteriostatic/both

A

individually bacteriostatic together bactericidal synergetic

36
Q

macrolides, lincosamides and streptogramins B

A

cross-resistance due to similar mechanisms of action

37
Q

constitutive

A

present all the time

38
Q

erm

A

the gene that is targeted for alter drug target for resistance against MLSb

39
Q

inducible

A

there but not expressed until needed

40
Q

constitutive is high/low fitness cost compared to inducible

A

high

41
Q

D-test

A

shows inducible

42
Q

Constitutively resistant to macrolide (ERY) and lincosamide (CL)

Constitutively resistant to ERY, sensitive to CL

Constitutively resistant to ERY, inducibly resistant to CL

A
43
Q

You streak bacteria from inside the red zone to a new plate and place a fresh CL disk without an ERY disk nearby. What do you expect to see after incubation for 24h?

A.A symetrical, circular zone

B.No zone

C.A D-shaped zone

A

A.No zone

44
Q

oxazolidinones bind to the 30S/50S

A

50S

45
Q

oxazolidinones are bacteriostatic/bactericidal

A

bacteriostatix

46
Q

oxazolidinones work against

A

gram +

47
Q

subclass of oxazolidinones

A

linezolid

48
Q

resistance to oxazolidinones

A

alter drug target mutations in rRNA

49
Q

isoniazid

A

targets mycolic acid synthesis

50
Q

ethambutol

A

thought to inhibit arabinotransferases

51
Q

lipopeptides

A

disrupt the cell membrane of G+ bacteria

52
Q

lipopetide example

A

daptomycin

53
Q

folate syntheiss inhibitors

A

trimethoprim

sulfonamides

54
Q

RNA synthesis inhibitors

A

rifamycin

55
Q

DNA synthesis inhibitors

A

fluoroduinolones

56
Q

agents thatr damage DNA

A

nitroimidazoles

57
Q

Which of the following is NOT traditionally used as a b-lactam antibiotic?

A.Cephalosporin

B.Monobactam

C.Penicillim

D.Clavulanic acid

A

D.Clavulanic acid

58
Q

Which of the following targets the bacterial tetrahydrofolate synthesis pathway?

A.Fluoroquinolone

B.Trimethoprim

C.Rifamycin

D.Macrolide

A

B.Trimethoprim

59
Q

Mutations in bacterial topoisomerases confer resistance to which of the following?

A.Ceftriaxone

B.Ciprofloxacin

C.Chloramphenicol

D.Clindamycin

A

B.Ciprofloxacin

60
Q

Which class of bacteria is most susceptible to b-lactam antibiotics?

A.Gram-negative

B.Gram-positive

C.Mycobacteria

D.Mycoplasma

A

B.Gram-positive

61
Q

b-lactams bind tightly to M. tuberculosis PBPs

Yet, Mtb is resistant to b-lactams – HOW?

A

Mycobacterium tuberculosis produces several b-lactamases

62
Q

For which of the following S. aureus infections would you NOT prescribe daptomycin (a lipo-peptide antibiotic)?

A.Osteomyelitis (bone infection)

B.Pneumonia (lower respiratory tract infection)

C.Endocarditis (heart valve infection)

D.Bacteremia (blood stream infection)

A

B.Pneumonia (lower respiratory tract infection)

63
Q

T/F Antibiotic resistance often exacts a
fitness cost

A

True

64
Q

VanA locus*

A

constitutive resistance

65
Q

VanB locus*

A

inducible resistance

66
Q
A

Immunology (14 decks)

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