Antimicrobials: Mechanism of Action

Question 1

Class: Cell Wall Synthesis Inhibitors

Answer 1

Inhibit cell wall formation via altering: 1. Transpeptidase 2. With or without B-Lactam structure 3. D-ala D-ala 4. membrane potential

Question 2

Class: Protein Synthesis Inhibitors

Answer 2

Inhibit protein binding via altering: 1. 30S 2. 50S 3. tRNA Isoleucine transport 4. Formation of 70S

Question 3

Class: Folic Acid Synthesis Inhibitors

Answer 3

Inhibit folic acid synthesis via altering: 1. Dihydropterate reductase 2. Difydrofolate reductase

Question 4

Class: DNA/RNA Synthesis Inhibitors

Answer 4

Inhibit DNA/RNA synthesis by altering: 1. gyrase 2. topoisomerase 3. depolarizing–>toxic effect 4. ferrodoxin metabolism–>toxic effect 5. electron transfer 6. mutagenesis

Question 5

Class: Antimycobacterials

Answer 5

Inhibit mycobacterium growth via: 1. Mycolic acid synthesis 2. RNA polymerase 3. pH altering 4. RNA synthesis

Question 6

Penicillin Class Action

Answer 6

B-Lactam binds transpeptidase

Question 7

Penicillinase-resistant penicillins: Dicloxicillin, Methicillin, Oxacillin, Nafcillin

Answer 7

Side groups protect these B-Lactams from B-lactamase

Question 8

Irreversible B-lactamase inhibitors

Answer 8

Combined with penicillins to broaden spectrum of treatment

Question 9

Cephalosporins

Answer 9

B-lactam that is stable at low pH

Question 10

Carbapenams

Answer 10

Penicillin effect without B-lactam structure

Question 11

Televancin and Vancomycin

Answer 11

Block polymerization by binding D-Ala D-Ala

Question 12

Aminoglycosides: Amikacin, Gentamycin, Kanamycin, Netilmicin, Streptomycin, Tobramycin, Neomycin

Answer 12

30S binding interferes with initiation misreading dissociation

Question 13

Tetracyclines: Tetracycline, Minocycline, Doxycycline, Demeclocycline, Oxytetracycline, Tigecycline

Answer 13

30 binding prevents aa from polymerizing

Question 14

Chloramphenicol

Answer 14

50S binding interfers with peptidyl transferase

Question 15

Lincosamides: Clindamycin

Answer 15

50S binding prevents translocation from A site to P site

Question 16

Macrolides: Erythromycin base/estolate/sterate/ethylsuccinate, Clatrithromycin, Azithromycin

Answer 16

50S binding prevents translocation from A site to P site

Question 17

Ketolides: Telithromycin

Answer 17

50S binding to two sites decreases resistance

Question 18

Retapamulin

Answer 18

50S binding incactivates peptidyl transferase and blocks the P site

Question 19

Mupirocin

Answer 19

Inhibits tRNA transport of Isoleucine

Question 20

Linezolid

Answer 20

50S binding prevents 70S subunit aggregation

Question 21

Streptogramins: Combination of Quinupristan Dalfopristin

Answer 21

Dalfo: Early protein synthesis Quinu: Late protein synthesis

Question 22

Sulfonamides: Sulfadiazine, silver sulfadiazine, sulfisoxoasole, sulfamethoxazole, sulfacetamide, sulfasalazine

Answer 22

Compete with PABA for dyhydropteroate synthase (first step in folic acid production)

Question 23

Trimethoprim

Answer 23

Inhibits dihydrofolate reductase (last step in folic acid production)

Question 24

Fluoroquinolones: “-floxacin”

Answer 24

DNA gyrase topoisomerase IV

Question 25

Lipopeptides: Daptomycin

Answer 25

Rapid depolarization via binding membranes causes halt to DNA RNA synthesis

Question 26

Metronidazole

Answer 26

Anaerobic bacteria absorb Reduction with ferrodoxin Toxic metabolites halt DNA synthesis

Question 27

Nitozoxanide

Answer 27

Inhibit electron transfer via pyruvate/ferrodoxin oxidoreductase enzyme to stop DNA synthesis

Question 28

Tinidazole

Answer 28

Damages DNA

Question 29

Rifaximin

Answer 29

Binds DNA dependent RNA polymerase

Question 30

Isoniazid

Answer 30

Mycolic acid synthesis halted in mycobacterium

Question 31

Rifampin

Answer 31

RNA polymerase of mycobacteria

Question 32

Pyrazinamide

Answer 32

Lowers pH in tubercle cavity of mycobacterium

Question 33

Ethambutol

Answer 33

Inhibit RNA synthesis in mycobacterium

Question 34

Clofazimine

Answer 34

Binds DNA and inhibits RNA polymerase function in mycobacterium