18.6, bacterial diseases and antibiotics

• Bacteria


  Some bacteria can cause disease in plants and animals
• How bacteria can cause illness

  1. Bacteria can attack the cells in one of the body's tissues

  2. Bacteria can make poisons, called toxins, that can be carried in the blood to other parts of the body
• Diseases caused by bacteria

  • Tuberculosis (TB)
  • Food poisoning
• Antibiotics


  Chemicals that kill or slow the growth of bacteria
• How antibiotics work


  • Many antibiotics work by stopping bacteria from making cell walls
  • Antibiotics do not affect animal cells because animal cells do not have cell walls
  • Antibiotics do not affect viruses, because viruses do not have cell walls
• Importance of antibiotics


  • Antibiotics are very important medical treatments
  • Antibiotics should only be used when necessary
• Overuse of antibiotics


  Can kill the "good" bacteria in your digestive system, resulting in illness
• Antibiotics can be life-saving medicines
• The inappropriate and incomplete use of antibiotics has resulted in strains of bacteria that are not affected by antibiotics</b>
• Any bacteria that are resistant will survive and reproduce, and resistance can then be passed on to offspring and spread to other bacteria
• Factors that have contributed to antibiotic resistance

  • Overuse
  • Underuse
  • Misuse
• Overuse


  Anytime antibiotics are used, there is a chance to select for resistant bacteria. The unnecessary use of antibiotics increases the possibility that resistant bacteria will become more common.
• Underuse


  Antibiotics may make a person feel better after just one or two days. But the whole prescription of antibiotics must be taken. Otherwise, it is possible that only the weakest bacteria will be killed, and the ones with some resistance may survive.
• Misuse


  A large portion of the antibiotics used in the United States are fed to livestock, such as cows, to increase their growth. Antibiotics may therefore be added to the food of healthy animals. The misuse of antibiotics in agriculture can lead to antibiotic resistance of bacteria in the animals' food.