Antimicrobial Agents

Question 1

Beta-Lactam Drugs

Answer 1

MOA • inhibition of enzymes (transpeptidase) needed for peptidoglycan formation • formation of covalent complexes with enzymes

Question 2

Penicllins

Answer 2

MOA • binds to enzyme penicillin binding protein (transpeptidase) • to mediate transpeptidation reaction

Question 3

Cephalosporins

Answer 3

•can withstand the action of beta-lactamases •more modifiable •structurally similar to penicillin

Question 4

Glycopeptides

Answer 4

MOA • binds to terminal D-Ala-D-Ala of the pentapeptide-glycosyl peptidoglycan intermediates • binds to substrate (D-Ala, D-Ala)

Question 5

Glycopeptides

Answer 5

• interferes with cross-linking in peptidoglycan

Question 6

Cycloserine

Answer 6

MOA • inhibits synthesis of peptidoglycan precursors (D-Ala D-Ala) in the cytoplasm

Question 7

Bacitracin

Answer 7

MOA • inhibits transport of lipid-bound precursors across the cytoplasmic membrane

Question 8

Bacitracin

Answer 8

MOA • inhibits NAG and NAM synthesis

Question 9

Polymyxins

Answer 9

MOA • acts like detergents which interact with phospholipids

Question 10

Polymyxins

Answer 10

MOA • increases permeability and macromolecule leakage

Question 11

Folate

Answer 11

important DNA synthesis precursor

Question 12

Sulfonamides

Answer 12

MOA • competitive inhibition of folic acid synthesis • binds to dihydropteroate synthase

Question 13

Trimethoprim

Answer 13

MOA • blocks steps of tetrahydrofolase formation by dihydrofolate reductase prevention

Question 14

Trimethoprim

Answer 14

MOA • targets the folic acid pathway

Question 15

Fluoroquinolones

Answer 15

MOA • binds and interferes with DNA gyrase (for Gr -) and topoisomerase IV (for Gr +)

Question 16

Metronidazole

Answer 16

MOA • Nitro group is reduced by nitroreductase • responsible for DNA breakage due to chemical action

Question 17

Rifamycin

Answer 17

MOA • binds to DNA dependent RNA polymerase

Question 18

Chloramphenicol

Answer 18

MOA • inhibits translation through elongation step inhibition

Question 19

Macrolides

Answer 19

MOA • inhibits tRNA (transfer RNA) • inhibits translation by elongation inhibition through 23S RNA binding

Question 20

Oxazolidinones

Answer 20

MOA • inhibits initiation of mRNA translocation • inhibits protein synthesis by interacting with 23S RNA

Question 21

Tetracyclines and Doxycycline

Answer 21

MOA • inhibits protein synthesis by binding reversibly to the 30S ribosomal subunit

Question 22

Tetracycline and Doxycycline

Answer 22

targets intracellular pathogens

Question 23

Aminoglycosides

Answer 23

used with penicillins in order to diffuse and enter bacterial cell

Question 24

1st Line Drugs

Answer 24

Isoniazid Less side effects Pyrazinamide Rifampicin

Question 25

2nd Line Drugs

Answer 25

Streptomycin Ethambutol TB treatment (1st line resistant)

Question 26

Inhibition of Cell Wall Synthesis

Answer 26

Beta-Lactams Cycloserine Bacitracin

Question 27

Inhibition of Cell Membrane Function

Answer 27

Polymyxins

Question 28

Inhibitors of Folate Synthesis

Answer 28

Sulfonamides Trimethoprim

Question 29

Interference with DNA synthesis

Answer 29

Fluroquinolones Metronidazole

Question 30

Interference with RNA synthesis

Answer 30

Rifamycins

Question 31

Inhibition of Protein Synthesis 30S ribosome inhibition

Answer 31

Chloramphenicol Macrolides Oxazolidinones

Question 32

Inhibition of Protein Synthesis 30S ribosome inhibition

Answer 32

Tetracyclines Doxycyclines Aminoglycoside

Question 33

Streptomycin Gentamycin Tobramycin Amikacin Neomycin

Answer 33

Give aminoglycosides examples. ## Footnote *(Hint: There are five.)*

Question 34

Biological resistance

Answer 34

changes that results in observably ***reduced*** susceptibility of organism to a particular antimicrobial agent

Question 35

Clinical resistance

Answer 35

antimicrobial susceptibility has been ***lost***

Question 36

Intrinsic/inherent

Answer 36

resistance is *predictable*

Question 37

Acquired

Answer 37

resistance is *unpredictable*

Question 38

mefA

Answer 38

Give the gene. ## Footnote *Streptococcus pneumoniae*

Question 39

msrA

Answer 39

*Staphylococcus aureus* & *Enterococcus*

Question 40

mreA

Answer 40

*Streptococcus agalactiae*

Question 41

Lateral Gene Transfer

Answer 41

most important strategy of bacteria to spread resistance