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 ( ) 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

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