TEST 2 Antimicrobial Pharmacology 1 General principles

Question 1

Define Bactericidal agent?

Answer 1

• Ideal scenario for killing bacteria.
• Lethal to susceptible microorganisms
  
  • Penicillins and Cephalosporins

Question 2

Define Bacteriostatic Agent

Answer 2

• Inhibitory to growth of susceptible micro-organisms.
  
  • Sulfonamides

Question 3

Define Post-antibiotic effect (PAE)

Answer 3

• Persistent effect of an antimicrobial on bacterial growth following brief exposure of organisms to a drug.
  
  • Aminoglycosides & fluoroquinolones

Question 4

What mechanisms of action are used by antimicrobial agents

Answer 4

• CPM - CD
• Inhibitors of
  
  • Cell Wall synthesis
  • Protein synthesis or structure
  • Metabolism
• Interferes
  
  • Cell membrane function
  • DNA/RNA synthesis

Question 5

What antimicrobial agents inhibit Cell wall synthesis?

Answer 5

• PCCA - VBC
• Penicillins/Cephalosporins/Carbapenems/Aztreonam
• Vancomycin
• Bacitracin
• Cycloserine

Question 6

How do Penicillins/Cephalosporins/Carbapenems/Aztreonam inhibit cell wall synthesis?

Answer 6

Prevents cross-linking of peptidoglycan strands by inhibiting transpeptidases.

Question 7

How does Vancomycin inhibit cell wall synthesis?

Answer 7

Inhibits peptidoglycan synthetase and polymerization of linear peptide.

Question 8

Describe Aminoglycosides?

Answer 8

• Inhibits Protein Synthesis/structure
• Inhibits 30S ribosome
• Causes misreading of mRNA.

Question 9

Describe Chloramphenicol?

Answer 9

• Inhibits peptidyl transferase and peptide band formation

Question 10

Describe how Erythromycin, clindamycin, lincomycin inhibit protein synthesis?

Answer 10

Inhibits 50S ribosome

Question 11

Describe Tetracyclines

Answer 11

• Inhibits binding of aminoacyl tRNA to ribosome
• 30S ribosome

Question 12

What does Streptogramins/Linezolid effect?

Answer 12

• Inhibit protein synthesis/structure by acting on 23S ribosome.

Question 13

What is the effect of Rifampin?

Answer 13

Interference with DNA/RNA synthesis by inhibiting DNA-dependent RNA polymerase.

Question 14

What is the effect of Fluoroquinolones?

Answer 14

Interferes with supercoiling of DNA by action on DNA gyrase (topoisomerase II)

Question 15

What is the effect of Isoniazid and trimethoprim?

Answer 15

Prevents synthesis of lipids and thus disrupts metabolism

Question 16

What is the effect of Sulfonamides and trimethoprim?

Answer 16

Prevents synthesis of folic acid and thus disrupts metabolism

Question 17

What are the basic steps in Antimicrobial treatment?

Answer 17

1. Determine infection site
2. Determine causative organism
3. Select a drug based on:
   
   1. Sensitivity of the microorganism
   2. Physiochemical properties
   3. Toxicities of the drug
   4. Patient characteristics
4. Follow patient for clinical response
5. Alter therapy as necessary

Question 18

What are the 5 pharmacologic considerations

Answer 18

• Route of administration
• Distribution
• Routes of Elimination
• Drug interactions
• Allergies

Question 19

How do bacteria resist Penicillins/Cephalosporins?

Answer 19

• B-lactamases
• PBP changes
• Porin channel changes

Question 20

How do bacteria resist Aminoglycosides?

Answer 20

Enzyme Inactivating

Question 21

How do bacteria resist Macrolides?

Answer 21

Methyltransferases that alter
drug binding sites on 50S
ribosomal subunit

Question 22

How do bacteria resist Tetracyclines?

Answer 22

Transport systems that pump drug out of the cell.

Question 23

How do bacteria resist Sulfonamides?

Answer 23

Increased PABA formation
Target enzyme sensitivity

Question 24

How do bacteria resist Fluoroquinolones?

Answer 24

Target enzyme changes drug efflux

Question 25

What is the antimicrobial Ace in the hole?

Answer 25

Aztreonam (Anaphylaxis) AAA

Question 26

What is the last resort antimicrobial agent?

Answer 26

Colistin