4.4 Antibiotics Flashcards
Antibiotics are substances produced by microorganisms that…
Kill or inhibit bacteria
Antibiotics first developed in…
The 1930s and 1940s
Antibiotics are found in…
Other organisms but there are also synthetic antibiotics
Antibiotics kill bacteria by…
Interfering with their metabolism
Penicillin works by:
Stopping the bacteria synthesising new cell walls when the cells divide.
The cells swell up because they take in water by osmosis.
The weakened cell wall is not strong enough to withstand the pressure - so they burst
Several antibiotics stop…
Bacteria making proteins- chloramphenicol stops amino acids being brought to the ribosomes.
Tetracycline binds to bacterial ribosomes and stops proteins being made
Alexander Fleming discovered penicillin accidentally in…
1928
Fleming’s discovery:
- studying bacteria and left a Petri dish of bacteria in his lab while he went away on holiday
- returned and found that PENICILLIUM fungus had started growing in the dish, also noticed that the bacteria growing near the fungus had died
- thought that the fungus was producing a chemical that killed bacteria and he made an extract (penicillin) - couldn’t obtain enough to test it properly
In 1939, Ernst Chain and Howard Florey managed to obtain enough penicillin to test:
- found that it was effective in treating bacterial infections in mice
- 1941- carried out first trial of penicillin on a human
- used penicillin to treat a policeman who had osteomyelitis (infection of the bone and bone marrow)
- man did show some improvement but he died when supply ran out
- so short of penicillin- purified penicillin from the man’s urine to use again - created interest in penicillin
WWII was very important in the development if penicillin because:
British and US governments wanted to be able to use the drugs to reduce the number of soldiers dying from their wounds.
Florey and chain developed a method for growing penicillin that led to tens of thousands of soldiers’ lives being saved.
1945 Fleming Florey and Chain were jointly awarded the Nobel Prize for medicine
Penicillin was very limited during WWII
Ernest Duchesne was a French doctor and notices that the Arab stable boys at the army hospital kept the saddles in the dark, damp room so that mould could grow on them which helped…
Treat the saddle sores on the horses
Duchesne tested the mould in an investigation…
Took a suspension of the mould and injected it into guinea pigs that had a bacterial infection- they all recovered.
Duchesne also grew the fungus…
Penicillium glaucum with the bacterium Escherichia coli
Showed that the fungus completely killed the bacteria
Went on to inject an animal with enough typhoid bacteria to cause a lethal infection. However by injecting penicillium glaucum at the same time show that the animal didn’t become ill
