1. Antibiotic Resistant Bacteria
Noadswood Science, 2016

2. Antibiotic Resistant Bacteria
Friday, May 25, 2018
Antibiotic Resistant Bacteria
To describe how bacteria become resistant and the dangers of this

3. Precise Learning
Students should be able to explain the use of antibiotics and other medicines in treating disease.
Antibiotics, such as penicillin, are medicines that help to cure bacterial disease by killing infective bacteria inside the body. It is important that specific bacteria should be treated by specific antibiotics.
The use of antibiotics has greatly reduced deaths from infectious bacterial diseases.
However, the emergence of strains resistant to antibiotics is of great concern.
Antibiotics cannot kill viral pathogens.
Bacteria can evolve rapidly because they reproduce at a fast rate.
Mutations of bacterial pathogens produce new strains. Some strains might be resistant to antibiotics, and so are not killed. They survive and reproduce, so the population of the resistant strain rises. The resistant strain will then spread because people are not immune to it and there is no effective treatment
MRSA is resistant to antibiotics
To reduce the rate of development of antibiotic resistant strains:
doctors should not prescribe antibiotics inappropriately, such as treating non-serious or viral infections
patients should complete their course of antibiotics so all bacteria are killed and none survive to mutate and form resistant strains
the agricultural use of antibiotics should be restricted
The development of new antibiotics is costly and slow. It is unlikely to keep up with the emergence of new resistant strains

4. Antibiotics
Antibiotics are substances that kill bacteria or stop their growth (often targeting the bacteria’s cell capsule)
They do not work against viruses – it is difficult to develop drugs that kill viruses without also damaging the body’s tissues

5. Antibiotics Antibiotic Target Penicillin Breaks down cell walls
Erythromycin
Inhibits protein synthesis
Neomycin
Vancomycin
Ciprofloxacin
Inhibits DNA replication

6. Penicillin
The first antibiotic (penicillin) was discovered in 1928 by Alexander Fleming
He noticed that some bacteria he had left in a petri dish had been killed by naturally occurring penicillium mould
Since the discovery of penicillin, many other antibiotics have been discovered or developed – most antibiotics used in medicine have been altered chemically to make them more effective and safer for humans

7. Resistance
Bacterial strains can develop resistance to antibiotics, due to natural selection
In a large population of bacteria, there may be some cells that are not affected by the antibiotic – these cells survive and reproduce, producing even more bacteria that are not affected by the antibiotic
MRSA (methicillin-resistant staphylococcus aureus) – it is very dangerous because it is resistant to most antibiotics
It is important to avoid over-use of antibiotics, so we can slow down, or stop, the development of other strains of resistant bacteria

8. Resistance
Although vaccinations and antibiotics are useful in the fight against pathogens, bacteria and virii can mutate to form a new resistant ‘strains’...
Variation – some strains of bacteria are resistant
Competition – the non-resistant bacteria are killed by the penicillin
Survival of the fittest – the resistant bacteria survive
Reproduction – the resistant bacteria reproduce and pass on their adaptations to their offspring
Bacteria
Antibiotic

9. Bacterial Growth Which antibiotic is the best?
Using the agar plates spread bacteria evenly over them
Place some antibiotic disks randomly onto the culture (ensure you note which antibiotic plate is which)!
Which antibiotic is the best?
Which antibiotic are the bacteria most resistant to? A B C D E

10. Bacterial Growth
Using discs on agar covered with bacteria – this technique is used in hospitals on samples of urine, blood and stools to work out which antibiotic to use
The antibiotic disc which has the caused the widest circle in the bacterial plate is the best for that type of bacteria – it has killed the highest quantity of bacteria (C)
The antibiotic which the bacteria are most resistant too has the smallest circle (B) A B C D E

11. Cleanliness
One simple way to reduce the risk of infection is to maintain personal hygiene and to keep hospitals clean
In the 19th century Semmelweis realised the importance of cleanliness in hospitals – however, although his ideas were successful, they were ignored at the time because people did not know that diseases were caused by pathogens that could be killed

12. MRSA – Research
How can we control the spread of antibiotic resistant bacteria in hospitals?
Could we stop using antibiotics – why / why not?

13. Slowing Resistance
To slow the rate of development of resistant strains it is important for doctors to avoid over-prescribing antibiotics
It is also important for patients to finish the whole course of the antibiotics so all bacteria are killed and none survive to mutate and form resistant strains
Agricultural use of antibiotics should also be restricted

14. Defence

15. Practice Questions
True or false – painkillers can be used to tackle the cause of an infection
What are antibiotics and give an example
Who discovered penicillin and how was it discovered?
Chloe has flu – explain why a doctor will not give her antibiotics but recommends a painkiller. Suggest why the painkiller will not help clear Chloe’s infection any quicker

16. Answers
True or false – painkillers can be used to tackle the cause of an infection – false
What are antibiotics and give an example – drugs that kill / prevent the growth of bacteria, e.g. penicillin / methicillin
Who discovered penicillin and how was it discovered – Alexander Fleming (a Petri dish of bacteria had mould on it which was free of bacteria)
Chloe has flu – explain why a doctor will not give her antibiotics but recommends a painkiller. Suggest why the painkiller will not help clear Chloe’s infection any quicker – antibiotics do not kill viruses. The painkiller will help with the pain but won’t tackle the underlying cause of the flu