Drugs and Antibiotic Resistance

15.1 Drugs

• Definition: A substance taken into the body that modifies and affects chemical reactions. Typically derived from plants.
• Functions:
  • Cure diseases and heal wounds.
  • Induce hallucinations or feelings of excitement.
  • Prolong life.
  • Relieve pain.
• How drugs act in your body:
  • Mechanism described (refer to the provided YouTube links for a visual explanation).
    • https://www.youtube.com/watch?v=uOcpsXMJcJk&t=20s

15.2 Medicinal Drugs - Antibiotics

• Antibiotics: Substances that kill bacteria by damaging their cell walls without harming other living cells.
• Source: Often made from fungi (e.g., Penicillium sp.).
• Mechanism: Damage bacterial cell walls.
• Reason Fungi Produce Antibiotics: Fungi produce antibiotics to eliminate competing bacteria near them, as they vie for the same food resources.
• First Antibiotic: Penicillin, derived from the fungus Penicillium sp. (observed growing on decaying fruit).
• Effectiveness: Antibiotics are effective against bacteria but not against viruses.
• Antibiotic Resistance:
  • Selection Pressure: Introducing antibiotics creates selection pressure on bacteria to develop resistance.
  • The more antibiotics used, the greater the selection pressure for resistance.
• Example of Natural Selection: Antibiotic Resistance in Bacteria
  • When a person infected with bacteria is treated with penicillin, the bacteria are unable to grow new cell walls, and they burst open.
  • The chances of different bacteria to become resistant are quite low, but because there are so many bacteria, it could happen.
  • A mutant bacterium can reproduce and form a large population of resistant bacteria.
• MRSA (Methicillin-Resistant Staphylococcus Aureus):
  • A strain of bacteria (Staphylococcus aureus) resistant to several antibiotics.
  • Can cause infections that are difficult to treat.

Minimizing Development of Resistant Bacteria (e.g., MRSA)

• Strategies:
  • Use antibiotics only when essential.
  • Ensure the full treatment course is completed.
  • Prescribe/use antibiotics less often.
  • Avoid antibiotics for viral or fungal infections.
  • Ensure patients complete the entire course of antibiotics.
  • Develop new antibiotics.
  • Avoid prolonged use of the same antibiotics; rotate antibiotics.
  • Use combinations of antibiotics.
  • Implement other preventive measures (AVP), e.g., isolation of patients with antibiotic-resistant infections and good hygiene to prevent the spread of infection.

19.3 Selection – Ex of Natural Selection

• Key Concepts:
  • Variation
  • Survival of the fittest
  • Survivors survive and reproduce
  • Advantageous characteristics passed on to offspring