L4 Antimicrobial

Question 1

bacterias ribosomes _____ compared to human ribosomes that are ______

Answer 1

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

Question 2

classes of protein synthesis inhibitors that affect the 30S

Answer 2

1. aminoglycosides 2. tetracyclines

Question 3

classes of protein synthesis inhibitors that affect the 50S

Answer 3

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

Question 4

aminoglycosides are generally bactericidal/bacteriostatic/both

Answer 4

bactericidal

Question 5

aminoglycosides are generally used againist gram + /gram -

Answer 5

mainly used against gram -

Question 6

subclasses of aminoglycosides

Answer 6

subclasses: 1. streptomycin 2. gentamicin

Question 7

anaerobes/aerobes are resistant to aminoglycoside

Answer 7

anaerobes are intrinsically resistant

Question 8

resistance to aminoglycosides

Answer 8

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

Question 9

enzymes are usually encoded on mobile/stationary genetic elements

Answer 9

mobile

Question 10

combinational therapy

Answer 10

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

Question 11

B lactam and aminoglycoside combinational therapy

Answer 11

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

Question 12

tetracyclines bind to 30S/50S

Answer 12

30S

Question 13

mycoplasma

Answer 13

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

Question 14

B lactams would not be affective againist mycoplasm becuase

Answer 14

they do not have petidoglycan cell wall

Question 15

tetracyclines are generally bactericidal/bacteriostatic/both

Answer 15

bacteriostatic

Question 16

Subclasses of tetracyclines

Answer 16

tetracycline and doxycycline

Question 17

Tetracyclines attack

Answer 17

G+, G-, mycoplasma, and intracellular bacteria

Question 18

Which antibiotic would you use to kill intracellular bacteria?

Answer 18

Tetracyclines

Question 19

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

Answer 19

bacteria

Question 20

_______ and _______ inhibit the absorptions of tetracyclines

Answer 20

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

Question 21

contraindications of tetracycline

Answer 21

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

Question 22

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

Answer 22

true

Question 23

resistance to tetracyclines

Answer 23

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

Question 24

chloramphenicols are generally bactericidal/bacteriostatic/both

Answer 24

bacteriostatic but cidial against encapsulated organisms

Question 25

chloramphenicol bind to 30S/50S

Answer 25

50 S

Question 26

resistance to chloramphenicol

Answer 26

enzymatically inactivate drug (modified by acetyl transferases)

Question 27

macrolides are generally bactericidal/bacteriostatic/both

Answer 27

bacteriostatic

Question 28

macrolides bind to 30S/50S

Answer 28

50S

Question 29

macrolides subclasses

Answer 29

erythromycin and azithromycin

Question 30

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

Answer 30

gram + ; chlamydia

Question 31

lincosamides bind to 30S/50S

Answer 31

50S

Question 32

lincosamides are generally bactericidal/bacteriostatic/both

Answer 32

bacteriostatic

Question 33

subclass of lincosamide

Answer 33

clindamycin

Question 34

lincosamide is highly associated with

Answer 34

C difficile

Question 35

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

Answer 35

individually bacteriostatic together bactericidal synergetic

Question 36

macrolides, lincosamides and streptogramins B

Answer 36

cross-resistance due to similar mechanisms of action

Question 37

constitutive

Answer 37

present all the time

Question 38

erm

Answer 38

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

Question 39

inducible

Answer 39

there but not expressed until needed

Question 40

constitutive is high/low fitness cost compared to inducible

Answer 40

high

Question 41

D-test

Answer 41

shows inducible

Question 42

Constitutively resistant to macrolide (ERY) and lincosamide (CL) Constitutively resistant to ERY, sensitive to CL Constitutively resistant to ERY, inducibly resistant to CL

Answer 42

Question 43

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? ## Footnote A.A symetrical, circular zone B.No zone C.A D-shaped zone

Answer 43

A.No zone

Question 44

oxazolidinones bind to the 30S/50S

Answer 44

50S

Question 45

oxazolidinones are bacteriostatic/bactericidal

Answer 45

bacteriostatix

Question 46

oxazolidinones work against

Answer 46

gram +

Question 47

subclass of oxazolidinones

Answer 47

linezolid

Question 48

resistance to oxazolidinones

Answer 48

alter drug target mutations in rRNA

Question 49

isoniazid

Answer 49

targets mycolic acid synthesis

Question 50

ethambutol

Answer 50

thought to inhibit arabinotransferases

Question 51

lipopeptides

Answer 51

disrupt the cell membrane of G+ bacteria

Question 52

lipopetide example

Answer 52

daptomycin

Question 53

folate syntheiss inhibitors

Answer 53

trimethoprim sulfonamides

Question 54

RNA synthesis inhibitors

Answer 54

rifamycin

Question 55

DNA synthesis inhibitors

Answer 55

fluoroduinolones

Question 56

agents thatr damage DNA

Answer 56

nitroimidazoles

Question 57

Which of the following is NOT traditionally used as a b-lactam antibiotic? ## Footnote A.Cephalosporin B.Monobactam C.Penicillim D.Clavulanic acid

Answer 57

D.Clavulanic acid

Question 58

Which of the following targets the bacterial tetrahydrofolate synthesis pathway? ## Footnote A.Fluoroquinolone B.Trimethoprim C.Rifamycin D.Macrolide

Answer 58

B.Trimethoprim

Question 59

Mutations in bacterial topoisomerases confer resistance to which of the following? ## Footnote A.Ceftriaxone B.Ciprofloxacin C.Chloramphenicol D.Clindamycin

Answer 59

B.Ciprofloxacin

Question 60

Which class of bacteria is most susceptible to b-lactam antibiotics? ## Footnote A.Gram-negative B.Gram-positive C.Mycobacteria D.Mycoplasma

Answer 60

B.Gram-positive

Question 61

b-lactams bind tightly to M. tuberculosis PBPs Yet, Mtb is resistant to b-lactams – HOW?

Answer 61

Mycobacterium tuberculosis produces several b-lactamases

Question 62

For which of the following S. aureus infections would you NOT prescribe daptomycin (a lipo-peptide antibiotic)? ## Footnote A.Osteomyelitis (bone infection) B.Pneumonia (lower respiratory tract infection) C.Endocarditis (heart valve infection) D.Bacteremia (blood stream infection)

Answer 62

B.Pneumonia (lower respiratory tract infection)

Question 63

T/F Antibiotic resistance often exacts a fitness cost

Answer 63

True

Question 64

VanA locus\*

Answer 64

constitutive resistance

Question 65

VanB locus\*

Answer 65

inducible resistance