Antibiotics & Bacterial Resistance

Antibiotics Are natural substances that stops or destroys microorganisms by attacking metabolic pathways in the bacteria Example penicillin which works by preventing bacteria from constructing a normal cell wall Streptomycin works by preventing bacteria from manufacturing proteins

The first antibiotic 1928 – discovered by accident Alexander Fleming in St. Mary's Hospital, London (UK) He received the Nobel Prize in Medicine in 1945 along with his two colleagues He noticed a ring of inhibition of bacterial growth around a contaminant blue-green mould on a Staphylococcus plate culture.

The first antibiotic He then concluded that the mould was releasing a substance that was inhibiting bacterial growth and lysing (killing) the bacteria. He grew a pure culture of the mould and discovered that it was a Penicillium mould, now known to be Penicillium chrysogenum.

‘Age of Antibiotics’ Since the 1940s researchers have identified more then 2500 naturally occurring antibiotics that can be used to treat infections However, over the 50 years since, many disease-causing bacteria have become slowly resistant to the antibiotics

Antibiotic resistance Initially when a antibiotic is introduced into a system… it kills off the weaker strains of bacteria This leaves behind the strong strains These strong strains have slight variations within their genetic material which allow then to survive the antibiotic

These strong bacteria reproduce to pass on their strong fighting ability

Antibiotic use in animals A large percentage of antibiotics produced are used in livestock production in 3 ways… Therapeutic doses to treat disease Preventative doses to reduce risk of disease or death during production Low dose added to feed to promote growth

Non-therapeutic use of antibiotics in farm animals is a good or bad thing? Take 5 minutes and discuss with the person beside you whether it’s a good or bad thing to add antibiotic to livestock feed Think about… production rates, consumer thoughts, price of meat at the store, health of animals

What do you guys think?