Transcript B1.1 L7 Superbugs TBU

Superbugs
Starter
 Match the following keywords with your
definition sheet
Resistant Antibiotic Superbug Bacteria
Objective
 Understand the causes, affects and solutions
to the problems of bacterial superbugs
Outcomes
 State the definition of the keywords
 Describe the consequences of overuse of antibiotics
 Describe how strains of bacteria, including MRSA, have
developed resistance to antibiotics
 Can link the development of MRSA to the theory of
natural selection.
Superbugs
Keyword
Definition
Single-celled microorganisms
The capacity of an organism to
defend itself against a disease
a strain of bacteria that is resistant to
most antibiotics
A substance or compound that kills,
or inhibits the growth of, bacteria.
Superbugs
Keyword
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.
2.
3.
4.
5.
6.
What does MRSA stand for?
Where can you find MRSA?
How is MRSA transmitted?
Why is MRSA resistant?
What can MRSA cause?
What are the different causes of
MRSA?
MRSA
 What 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 Bacteria
 Apply 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, nonresistant 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 B
 Natural 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)