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Control of Pathogenic Bacteria

Control of Pathogenic Bacteria. Bacteria spread in various ways:. 1. moisture droplets in the air 2. dust 3. direct contact 4. fecal contamination 5. animal bites 6. wounds . Aseptic Techniques . (In addition to body’s own defence mechanisms ...) To prevent infection we use:

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Control of Pathogenic Bacteria

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  1. Control of Pathogenic Bacteria

  2. Bacteria spread in various ways: 1. moisture droplets in the air 2. dust 3. direct contact 4. fecal contamination 5. animal bites 6. wounds

  3. Aseptic Techniques (In addition to body’s own defence mechanisms ...) • To prevent infection we use: • autoclaves: sterilization of surgical equipment by extreme heat • protective clothing: masks, gowns, gloves • antiseptics: chemicals that kill bacteria (ex: alcohol, Lysol, etc) • air filtration: in operating rooms • extermination: kill animals that are carrying the disease

  4. Treatment of Active Infections (kill bacteria inside host) problem: You need to find a medication that kills bacteria, but won’t kill the host cells. solution: antibiotics • most important discovery of the last century • attack bacterial cell walls causing bacteria to die • not dangerous to humans or other animals • animal cells have no cell walls

  5. Discovery of Penicillin • discovered by Alexander Fleming (1929) • he cultured bacteria on agar • mould contaminated his plates aspergillus penicillium

  6. petri dish with nutrient agar bacterial colonies growing on agar mould colony zone of inhibition (no growth) Discovery of Penicillin

  7. Discovery of Penicillin • he observed a zone of inhibition: • (no bacterial growth) around the mould colony conclusion: mould produces a chemical (antibiotic) that kills bacteria i.e. He discovered penicillin.

  8. Antibiotics • since the discovery of penicillin, many antibiotics have been discovered • some ( > 2500) produced naturally by microorganisms • others synthetically

  9. Antibiotics • researchers must continue to find new antibiotics because: • different species of bacteria have different cell walls, therefore need different antibiotics to destroy them • bacteria evolve very quickly - mutate • if only one bacterium becomes resistant….. • they reproduce asexually (binary fission) so quickly (~ every 20 minutes - 7h → 1x106 bacteria) • can pass on antibiotic resistance to other species through sexual reproduction

  10. Antibiotic Resistance • Antibiotic resistance develops from genetic variations within a bacterial population • After first exposure to an antibiotic: • Weaker strains of bacteria are killed • Stronger antibiotic resistant strains survive and pass their resistance to the next generation FROM WHAT WE KNOW WHY SHOULD YOU ALWAYS TAKE ANTIBIOTICS FOR THE FULL LENGTH OF TIME?

  11. Homework • Page 127 # 1, 2, 4, 7

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