Antibiotic Resistant Bacteria Noadswood Science, 2016

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

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

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

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

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

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

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

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

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

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

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

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

Defence

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

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