natural selection

• Evolution


  An example of natural selection that supports Darwin's theory
• Development of resistance


  1. Random mutation occurs in bacterial genes

  2. Some mutations protect bacterial cell from antibiotic

  3. Bacteria without mutation die or cannot reproduce when antibiotic present
• The number of resistant strains has increased, partly due to the overuse and misuse of antibiotics
• MRSA


  Methicillin-resistant staphylococcus aureus, resistant to most antibiotics
• Ways to reduce development of antibiotic resistant strains

  • Doctors should not prescribe antibiotics inappropriately
  • Patients should always complete full course of antibiotics
  • Agricultural use of antibiotics should be restricted
• Many new antibiotics were discovered in 1950s and 1960s, but this has slowed greatly
• Recent concerns of increasing resistance have created the need for new antibiotics, but they are costly and very slow to develop
• Some scientists fear that we are fighting a losing battle against resistant bacteria, which may ultimately lead to people dying from simple infections