D6 Antibacterials
• Historical development of penicillin• How penicillin works• Patient compliance• Overprescription
Bacteria• Bacteria are single cells with a protective cell-wall made up of complex structures of Peptidoglucans
• They have a single chromosome- a plasmid• Anaerobic (no need of oxygen) or aerobic (need oxygen)• Some cause diseases, others are beneficial• Antibacterial are chemicals that prevent growth and
multiplication of bacteria
Early antibacterials• Trypan red, developed by the german chemist
Paul Erlich (1854-1915) to cure sleeping sickness
• Arsenamine, Salvarsan, was developed to cure syphilis. Paul Erlich responsible
• Prontosil, a sulpha drug, used against streptococcal bacteria (1935)
• Penicillin (1928)!
Fleming 1928
• Worked with Staphylococcus aureus• Left petri dish when he went on holiday• Discovered on comeback that it had moulded• The mould produced a substance that
inhibited growth of the bacteria• He called the substance penicillin, but didn’t
pursue his discovery
http://www.youtube.com/watch?v=7qeZLLhx5kU
Florey and Chain 1941• Learned how to isolate and purify penicillin• Used penicillin on policemen who was dying
from septicaemia (blood poisoning)• The structure of penicillin was determined in
1950’s- chemists could start synthesising it!• Fleming, Florey and Chain recieved the Noble
Prize in 1945
How penicillin works• Interferes with the enzyme that build the cell-
wall (which animal cells don’t have)• The weakened cell-wall disintegrates while the
bacterium grows, and it dies• Bacteria can become resistant by producing an
enzyme called penicillinase, which deactivates the penicillin
Benzylpencillin- has to be injected
Modifications of penicillin side chain
Beta-lactam-ring
Benzylpencillin potassium salt- more water soluble and less acidic
Piperacillin- broad spectrum antibiotic
Fluocloxacillin- is beta-lactamase stable
Amoxillin- better absorbed, used orally
Prescription of antibiotics
• It’s important to eat the whole cure of penicillin and to take it reguarly
• To not give the antibiotics to someone else• Specific bacteria crave different penicillins• Broad- and narrow-spectra penicillin• Combination of drugs can be used
Dangers with over-prescription
• Resistant bacteria• Kill ”the good” bacteria• Bacteria becomes immune- by mutation• Precribed although not needed
MRSA-bacteria
• Metillicin- Resistant Staphylococcus Aureus• The ”super bug”• Makes beta-lactamase which degrades
penicillin
Meticillin
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