Lecture 23 - Antimicrobials Pt 2

Cell wall

• β-lactam – transpeptidase
• Vancomycin – transglycosylase and transpeptidase
• Bacitracin – bactoprenol

Ribosome (70s)

• Chloramphenicol - large ribosomal subunit
• Tetracycline - small ribosomal subunit

Metabolism

Sulfonamide/trimethoprim block folic acid anabolism

Mode of action

The way a drug affects microbes at the cellular level.

Cell membrane

Target: LPS
Polymyxin

• Lipophilic

• Not good selective toxicity

• Used in topical ointments

• Last resort intravenous use

Rifampin (RNA)

semi-synthetic antibiotic
Target: Bacterial RNA polymerase
Can cause liver toxicity

Fluoroquinolones (DNA)

semi-synthetic
Target: Topoisomerases

Antifungals

• Cell wall

• Targets: ergosterol synthesis, glucans, chitin, polyenes

• Imadazole

• fungicidal

• synthetic antifungal

Antivirals

Target nucleic acid synthesis

Acyclovir

• synthetic antiviral

Specificity: viral enzyme activation & viral DNA pol

• Neurotoxic metabolites

Vaccines

Classifying adaptive immunity
• Active adaptive immunity
• Activate/improve own immunity
• Passive adaptive immunity
• Transfer immunity
• Natural and artificial

Goal: produce B-memory cells

Benefits: Skip initial infection

Classifying adaptive immunity
Active adaptive immunity

• Activate/improve own immunity

Passive Adaptive Immunity

• Transfer Immunity

Natural and artificial

Passive

Comes from elsewhere

Active

Comes from individuals body

Naturally acquired and passive

Immunity acquired from antibodies passed in breast milk r through placenta

Artificially acquired and passive

Immunity gained through antibodies harvested form another person or animal

Naturally acquired and active

Immunity gained through illness and recovery

Artificially acquired and active

Immunity acquired though a vaccine

Vaccination

Artificial active immunity
(vaccines)
• Edward Jenner (1749-1823)

• Before him was
  variolation – ancient
  inoculation
  • Creates herd immunity –
  very few susceptible;
  everyone else protected.

Classes of vaccines

1. Live attenuated vaccines

2. Inactivated vaccines

3. Subunit vaccines

4. Toxoid vaccines

Live attenuated vaccines

Pathogen weakened genetically
• Positive – Can be passed to others. Strong memory.
• Negative - Can lead to a full-
blown disease if reversion occurs. Need gene knowledge.
Examples: chickenpox, measles, tuberculosis.

Inactivated vaccines

Pathogen killed
Protein antigens preserved
• Positive – No active infection,
weaker symptoms.
• Negative – Need high doses/multiple boosters. Cannot be passed on.
• Examples: cholera, hep A, rabies,
influenza

Subunit vaccines

• Just antigens: minimal side effects but need boosters (hepB)

• Conjugate vaccines - for pathogens with weak antigen. Just add a strong antigen to weak antigen. Ex: add capsule protein to antigen

Toxoid vaccines

Use toxins instead of antigens (botulism)