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Drugs

  • A drug is any substance taken into the body that modifies or affects chemical reactions in the body.

Use of antibiotics

  • Antibiotics are a distinct class of drugs used to treat infections.
    • They are used for the treatment of bacterial infecttions.
  • They work by **disrupting the cellular processes of bacteria (e.g. preventing them from building cell walls/reproducing), killing them or stopping their growth.
  • Antibiotics do NOT affect viruses.

Why antibiotics can’t kill viruses

  • Bacteria are living cells with their own metabolic pathways and structures (such as cell walls).
  • Viruses are non-living particles that do not have their own cell walls, cell membranes, or independent transport systems. Instead, they hijack your body’s own cells to reproduce.
    • Antibiotics target bacterial structures specifically, rendering it useless against viral infections (e.g. common cold, flu, chickenpox).

Antibiotic resistance

Issue

  • Some bacteria possess genes that make them resistant to specific antibiotics. When an antibiotic is used, these resistant bacteria are not killed, which significantly reduces the effectiveness of the drug.

Development of antibiotic resistance (natural selection)

  1. Random mutation. Within a population of bacteria, some individuals undergo random genetic mutations. A mutation may accidentally give a bacterium a gene that makes it resistant to a specific antibiotic.
  2. Selection pressure. When a person takes an antibiotic, the drug acts as a selection pressure. It kills off all the normal, vulnerable bacteria.
  3. Survival. The mutant, resistant bacteria survive the antibiotic treatment.
  4. Reproduction. With their competitors wiped out, the surviving resistant bacteria have more resources. They multiply rapidly, passing on the gene for antibiotic resistance to their offspring.
  5. Spread. Over time, the entire population becomes resistant, creating a strain of superbugs.

MRSA (Methicillin-Resistant Staphylococcus aureus)

  • MRSA is an example of a dangerous bacterium that has developed resistance to many commonly used antibiotics. It is problematic in hospitals where open wounds and weakened immune systems are common.

Limiting the development of resistant bacteria

  • No prescriptions for viral infections: Doctors shoulld never prescribe antibiotics for colds or sore throats caused by viruses.
  • Complete the full course: Patients must finish their entire prescribed course of antibiotics, even if they feel better. Stopping early leaves the most resillient bacteria alive to mutate and replicate.
  • Restrict agricultural use: Avoid using antibiotics as growth promoters in livestock farming, as this introduces low levels of drugs into the environment, accelerating resistance.
  • Hygeine controls: Maintaining strict hygeine in medical settings prevents the spread of existing resistant strains like MRSA.