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Antibiotic Resistance

Discovering Antibiotics

Alexander Fleming- 1928

Left his culture of bacteria exposed overnight. Found that mold growing on the plate seemed to kill the bacteria.

Called it penicillin.

(All antibiotics end with –in)

How do antibiotics work?

Kills bacteria by targeting their life processes. Example: Breaks down

cell wall

Able to target bacteria only-not viruses, cells, or cancerous cells.

Different antibiotics target different parts of the bacteria. Example: Some

antibiotics can stop a bacteria from breaking down food leaving it to die slowly.

Killing the bacteria

Breaks down the cell wall

Breaks down the DNA

+Evolution and Bacteria

•Slowly bacteria arose that were resistant to penicillin.

•They were resistant because their DNA was different and allowed them to survive in the presence of penicillin.

•As these resistant bacteria survived and reproduced there were many bacterial diseases that weren’t cured by penicillin anymore!

+Antibiotic Resistance

Bacteria could also transfer their resistance to other bacteria through:

1. Plasmid Transfer- The bacteria’s circular DNA replicated and transferred to other bacteria.

2. Viral Delivery- A bacteria that was infected by a virus could pass on their DNA through the virus.

3. Free DNA- A Bacteria dies but its DNA is free to join another bacteria.

Example: Staph aureus

Staph Infections- Occur most frequently in hospitals.

Bacteria are resistant to anti-microbial soap and many types of antibiotics.

+Analogy

If bacteria is an army…

Once swords were invented…they invented armor

Once guns were invented…they invented bullet proof vests

Once biological warfare was invented…they invented gas masks.

They are always trying to make it harder to kill them. (Example: Taliban hide and don’t wear uniforms-how can we find them?)

+What can I do?

Don’t use anti-microbial gels like Germ-X too often. It adds to the resistance of bacteria.

When you take an antibiotic you have to finish the whole bottle. By not finishing the bottle you are leaving the strongest most resistant bacteria to survive.

Don’t take antibiotics unless you have to.

+Review

1. Who discovered penicillin?_______________

2. What does an anti-biotic target in the bacteria?

3. What are the three ways a bacteria can transfer resistance to another bacteria?

4. What can you do to stop bacteria from becoming too resistant?