IA. General microbiology| 7. Antimicrobial drugs that inhibit the nucleic acid synthesis and alter the membrane function.

Question 1

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
1. What are the most common types of inhibition of nucleic acid synthesis?

Answer 1

1. Inhibition of folic acid synthesis
2. Inhibition of DNA gyrase
3. Inhibition of RNA synthesis

Question 2

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
2A. What are the 2 drugs that inhibit folate synthesis?

Answer 2

sulphonamides, trimethoprim

Question 3

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
2B. Make a diagram that demonstrate inhibitors of folate synthesis

Answer 3

Question 4

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
3A. What are the drugs that inhibit DNA gyrase?

Answer 4

Quinolones inhibit dna gyrase

Question 5

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
3B. What are the features of Quinolones

Answer 5

• Quinolones inhibit dna gyrase
• Original compound: nalidixic acid
• Fluoroquinolones: Ciprofloxacin, ofloxacin, norfloxacin, sparfloxacin
• Wide spectrum
• Newer FQs - mainly against gram-positive upper RTI
  +) Levofloxacin, moxifloxacin, gatifloxacin, gemifloxacin
• Not in pregnancy or young children

Question 6

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
3C. What are examples of Fluoroquinolones?

Answer 6

• Ciprofloxacin
• Ofloxacin
• Norfloxacin
• Sparfloxacin
  (CONS)

Question 7

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
3D. What are examples of Newer FQs - mainly against gram-positive upper RTI?

Answer 7

• Levofloxacin
• Moxifloxacin
• Gatifloxacin
• Gemifloxacin
  (LMGG)

Question 8

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
4. What is the role of Metronidazol?

Answer 8

• Against anaerobes + some protozoa
• Directly breaks down DNA
• Activated in the host cells by reduction of the nitro groups at low redox potential anaerobes

Question 9

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
5A. An example of the drug that inhibit RNA synthesis?

Answer 9

Rifampin

Question 10

I. Antimicrobial drugs that inhibit the nucleic acid synthesis
5B. What are the features of Rifampin?

Answer 10

• Inhibition of DNA dependent RNA polymerase by binding to its β subunit
• If polymerisation has started already, it is ineffective
• Paints tear orange

Question 11

II. Antimicrobial drugs that alter the function of Cell Membrane
1. What are the 2 drugs that alter the function of Cell Membrane?

Answer 11

1. Polymyxins (Colistin = polymyxin E)
2. Lipopeptides (daptomycin)

Question 12

II. Antimicrobial drugs that alter the function of Cell Membrane
2. What are the features of Polymyxins (Colistin = polymyxin E)?

Answer 12

• Cyclic polypeptidase
• Disintegration of cell membrane (bactericidal)
• Against gram-negative, for local treatment
• Proteus is resistant
• Nephrotoxicity → rapid deterioration in the kidney function due to toxic effect of medications and chemicals

Question 13

II. Antimicrobial drugs that alter the function of Cell Membrane
2. What are the features of Lipopeptides (daptomycin)?

Answer 13

• Against gram positive bacteria and MRSA
• Low side effects and low resistance