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

January 9, 2016 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

January 9, 2016 Treatment of Active Infections (kill bacteria inside host) problem: 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  no cell walls

January 9, 2016 Discovery of Penicillin discovered by Alexander Fleming (1929) cultured bacteria on agar mould contaminated his plates aspergillus penicillium

January 9, 2016 Discovery of Penicillin bacterial colonies growing on agar petri dish with nutrient agar zone of inhibition (no growth) mould colony

January 9, 2016 Discovery of Penicillin observed a zone of inhibition:  (no bacterial growth) around the mould colony conclusion: mould produces a chemical (antibiotic) that kills bacteria i.e. discovered penicillin

January 9, 2016 Antibiotics since the discovery of penicillin, many antibiotics have been discovered some ( > 2500) produced naturally by microorganisms others synthetically

January 9, 2016 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….. i.they reproduce asexually (binary fission) so quickly (~ every 20 minutes - 7h → 1x10 6 bacteria) ii.can pass on antibiotic resistance to other species through sexual reproduction

January 9, 2016 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?

January 9, 2016 Homework Page 127 # 1, 2, 4, 7