1. ANTIBIOTIC RESISTANCE
© 2016 Paul Billiet ODWS

2. Fast breeders Bacteria reproduce very quickly
Eschericia coli can complete a life cycle in 30 minutes
E. Coli
© 2016 Paul Billiet ODWS

3. Sex in bacteria Bacteria do exchange genes forming new combinations
Bacteria exchange genes by conjugation
This involves the transfer of genetic material via a cytoplasmic bridge between the two organisms
This can be done between unrelated species of bacteria
Recent studies on bacteria in the wild show that it definitely occurs in the soil, in freshwater and oceans and inside living organisms.
© 2016 Paul Billiet ODWS

4. The magic bullet Antibiotics revolutionised medicine
The first antibiotic, penicillin, was discovered by Alexander Fleming in 1929
It was later isolated by Florey and Chain.
© 2016 Paul Billiet ODWS

5. Antibiotics
Penecillin was not extensively used until the 2nd World War when it was used to treat war wounds
After 2nd World War many more antibiotics were developed
Today about 150 types are used
Most are inhibitors of the protein synthesis, blocking the 70S ribosome, which is characteristic of prokaryotes.
© 2016 Paul Billiet ODWS

6. Resistance <20 years for bacteria to show signs of resistance
Staphylococcus aureus (blood poisoning and pneumonia) started to show resistance in the 1950s
Today there are different strains of S. aureus resistant to every form of antibiotic in use.
© 2016 Paul Billiet ODWS

7. Multiple resistance
Some resistance was already naturally present in bacterial populations
Antibiotics added to their environment in higher concentrations increased the pressure by natural selection
Resistant bacteria that survive, rapidly multiplied
Passed their resistant genes on to other bacteria (both disease causing pathogens and non-pathogens).
© 2016 Paul Billiet ODWS

8. Transposons & Integrons
Resistance genes are often associated with transposons, genes that easily move from one bacterium to another
Many bacteria also possess integrons, pieces of DNA that accumulate new genes
Gradually a strain of a bacterium can build up a whole range of resistance genes
This is multiple resistance
These may then be passed on in a group to other strains or other species
© 2016 Paul Billiet ODWS

9. Antibiotics promote resistance
If a patient taking a course of antibiotic treatment does not complete it (or forgets to take it)…
the resistant strains get a chance to build up
Antibiotics also kill innocent bystanders, bacteria which are non-pathogens
Reduced competition for the resistant pathogens
Use of antibiotics also promotes antibiotic resistance in non-pathogens too
These non-pathogens may later pass their resistance genes on to pathogens
© 2016 Paul Billiet ODWS

10. Resistance gets around
When antibiotics are used on a person, then antibiotic resistant bacteria increase in other members of the family
In places where antibiotics are used extensively e.g. hospitals and farms antibiotic resistant strains increase.
© 2016 Paul Billiet ODWS

11. Antibiotic use and abuse
Viral infections not stopped by antibiotics
Doctors still prescribe (or are coerced into prescribing) antibiotics to treat them.
© 2016 Paul Billiet ODWS