1. 18.6 Bacterial Diseases and Antibiotics KEY CONCEPT Understanding bacteria is necessary to prevent and treat disease.

2. 18.6 Bacterial Diseases and Antibiotics Some bacteria cause disease. Bacteria cause disease by invading tissues or making toxins. A toxin is a poison released by an organism.

3. 18.6 Bacterial Diseases and Antibiotics Antibiotics are used to fight bacterial disease. Antibiotic: Chemicals that kill or slow the growth of bacteria. –Work by breaking down the cell wall of bacteria.

4. 18.6 Bacterial Diseases and Antibiotics –immune system may be lowered Normally harmless bacteria can become destructive.

5. 18.6 Bacterial Diseases and Antibiotics Bacteria can evolve resistance to bacteria Creates selective pressure that favors the bacteria they intended to destroy. Failure to take entire course of antibiotics - doesn’t destroy them all. Antibiotics fed to livestock

6. 18.6 Bacterial Diseases and Antibiotics Bacteria can evolve resistance to antibiotics. A bacterium carries genes for antibiotic resistance on a plasmid. A copy of the plasmid is transferred through conjugation. Resistance is quickly spread through many bacteria.