Control of Pathogenic Bacteria. Bacteria spread in various ways: 1. moisture droplets in the air 2....
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Transcript of Control of Pathogenic Bacteria. Bacteria spread in various ways: 1. moisture droplets in the air 2....
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
April 21, 2023
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
April 21, 2023
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
April 21, 2023
Discovery of Penicillin
• discovered by Alexander Fleming (1929)
• cultured bacteria on agar
• mould contaminated his plates
aspergillus penicillium
April 21, 2023
Discovery of Penicillin
bacterial colonies growing on agar
petri dish with nutrient agar
zone of inhibition (no growth)
mould colony
April 21, 2023
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
April 21, 2023
Antibiotics
• since the discovery of penicillin, many antibiotics have been discovered
• some ( > 2500) produced naturally by microorganisms• others synthetically
April 21, 2023
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 → 1x106 bacteria)
ii. can pass on antibiotic resistance to other species through sexual reproduction
April 21, 2023
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?
April 21, 2023
Homework
• Page 127 # 1, 2, 4, 7