Superbugs

Starter Match the following keywords with your

definition sheet

Resistant Antibiotic Superbug Bacteria

ObjectiveUnderstand the causes, affects and solutions to the

problems of bacterial superbugs

Outcomes State the definition of the keywordsDescribe the consequences of overuse of antibioticsDescribe how strains of bacteria, including MRSA, have developed

resistance to antibiotics Can link the development of MRSA to the theory of natural selection.

SuperbugsKeyword Definition

Single-celled microorganisms

The capacity of an organism to defend itself against a diseasea strain of bacteria that is resistant to most antibioticsA substance or compound that kills, or inhibits the growth of, bacteria.

SuperbugsKeyword Definition

Bacteria Single-celled microorganisms

Resistant The capacity of an organism to defend itself against a disease

Superbug a strain of bacteria that is resistant to most antibiotics

Antibiotic A substance or compound that kills, or inhibits the growth of, bacteria.

This little bacteria can.....

MRSA under a microscope

....cause this

MRSA http://www.nhs.uk/conditions/MRSA/Pages/Introduction.aspx

Read the article ‘What is MRSA’ to answer the following:

1.What does MRSA stand for?2.Where can you find MRSA?3.How is MRSA transmitted?4.Why is MRSA resistant?5.What can MRSA cause?6.What are the different causes of MRSA?

MRSAWhat does MRSA stand for?Methicillin-resistant Staphylococcus aureus

Where can you find MRSA?Many people naturally carry it on their throat, nose and skin

What can MRSA cause?A mild infection such as pimples and impetigo, if it penetrates

get through the skin and cause serious infection elsewhere in the body such as sepsis (blood infection) and pneumonia.

Natural Selection

Variation exists in a population due to mutations in their genes

The organisms with the most appropriate characteristics to their environment will survive and reproduce

The ‘useful’ gene that enabled them to survive will be passed on to the next generation

Natural Selection

Different Cheetahs within a population could run at different speeds due to variations (caused by mutations)

in their genes.

The fastest Cheetahs were able to catch more prey (Gazelles)therefore able to survive and reproduce.

The ‘useful’ genes that enabled them to run faster than others in the population, were passed on to the next .

Natural Selection of Bacteria

Natural Selection of BacteriaApply your knowledge of natural selection and

explain how bacteria develop resistance to antibiotics

A.Draw a flow diagram to show how can a strain of Staphylococcus aureus can become a resistant strain or MRSA

B.Write a paragraph describing why MRSA is a good example of natural selection in action. (6 marks)

Plenary

Peer mark your partners work and give them a mark out of 4 for each question

Give them a target for improvement

Question A Variation exists in S.aureus population due to

mutations in their genes When S.aureus are exposed to an antibiotic, non-

resistant pathogens are killed, the few with resistance will survive

The resistant S.aureus will reproduce and pass on the resistant gene to all offspring (bacteria reproduce asexually)

S.aureus will become MRSA when exposed to a high number of different antibiotics and the above is repeated

Question BNatural selection states that only those that are best

adapted to their environment will survive (1)MRSA has adapted to its environment, by being able

to resist various antibiotics (1)Non-resistant strains, like S.aureus, die out (1)As they are not well adapted to their environment

(1)All bacteria are able to reproduce quickly (1)Therefore mutations are seen in whole populations

very quickly (1)