(5.1+2) Antimicrobial Agents

Question 1

How do the three main types of influenza virus differ from their severity?

Answer 1

• Influenza A: most severe, multi hosts
• Influenza B: less severe, no animal hosts
• Influenza C: cold like symptoms

Question 2

Briefly describe the main steps involved in viral replication for the Influenza virus.

Answer 2

1. Binding and absorbing host cell via viral surface glycoproteins
2. Endocytosis via ATP dependent entry into endosome
3. H+ follows virus into endosome using M2 ion channel, low pH causing viral to uncoat
4. RNA synthesis and replication
5. Viral release requiring Nuraminidase, which prevent adhesion with host cell

Question 3

Suggest 2 groups of antibiotic that target DNA synthesis

Answer 3

• Quinolones (stops DNA replication)

- Trimethoprim (Folic acid antagonist)

Question 4

Suggest a group of antibiotic that targets nuclei acid synthesis.

Answer 4

Metronidazole

Question 5

Suggest 3 groups of antibiotic that targets protein synthesis

Answer 5

• Aminoglycoside
• Macrolides
• Tetracycline

Question 6

Suggest 2 groups of antibiotic that targets cell wall

Answer 6

• Beta lactam

- Vancomycin

Question 7

A patient with penicillin allergy, what drugs should be avoided?

Answer 7

• Amoxicillin, Methiciline etc

- Others in Beta lactam group: Cephalosporin, Carpenem

Question 8

Suggest two groups of antibiotic that require close drug monitoring and why?

Answer 8

• Aminoglycoside
• Vancomysin
• To ensure non-toxic doses

Question 9

Briefly describe the ways bacteria become resistance to antibiotics.

Answer 9

• Intrinsic: genetic mutation

- Extrinsic: Transformation (uptake of naked DNA), Conjugation (uptake of plasmid), Transduction (via bacteriophages)

Question 10

How do Amantadine and Rimantadine act as antiviral agents? Which of these is generally preferred and why?

Answer 10

• M2 ion channel blocker: H+ cannot enter endosome with virus -> without low pH -> virus cannot lose its Nucleocapsid coat
• Rimantadine is preferred due to less ADRs

Question 11

Suggest two M2 ion channel blockers. And suggest 5 ADRs of these.

Answer 11

• Amantadine & Rimantadine

- GI disturbance, hypotension, insomnia, confusion, dizziness

Question 12

How does Tamiflu act as an antiviral agent?

Answer 12

Neuraminidase inhibitor -> virus remain adhered with host cell via surface glycoprotein -> cannot escape to infect other cells

Question 13

Suggest two antiviral agents that interfere with the release of virus from host cell. And suggest 3 ADRs of these

Answer 13

Neuraminidase inhibitor

• Zanamivir
• Oseltamivir (Tamiflu)
• GI disturbance, headache, epistaxis

Question 14

What viruses can M2 ion channel blockers be used against?

Answer 14

Influenza A

Question 15

What viruses can Neuraminidase be used against?

Answer 15

Influenza A & B

Question 16

What is antigenic shift?

Answer 16

• Co-infection of subtypes -> recombination of binnding sites -> new strain

Question 17

What is antigenic drift?

Answer 17

• Small genetic mutation of binding site -> accumulation -> new strain
• e.g. Influenza A & B

Question 18

Suggest three complications of influenza viral infection.

Answer 18

• Sinusitis
• Bronchitis
• Pneumonia