3. 2. 3 - Evolutionary race between pathogens and medicines

Question 1

Why do medicines we develop to destroy pathogens quickly become ineffective?

Answer 1

• due to mutation, adaptation and natural selection of pathogens
• pathogens are in an evolutionary race against us and medicine we create to treat the disease they cause

Pathogens = disease causing organism

Question 2

What does it mean for a bacteria to become resistant?

Answer 2

The bacteria will not be affected by an antibiotic

Question 3

What is the evolutionary race between medicine and pathogens?

Answer 3

• penicillin was discovered to treat bacterial pathogens
• penicillin didn’t kill all types of bacteria
• many bacteria had become resistant to penicillin within a year of the medicine being prescribed
• natural selection: those bacteria became prevalent and bacterial infections were no longer affected by penicillin
• produced a new antibiotic called methicillin
• then methicillin resistant bacteria soon spread through bacterial populations

Question 4

Apply GENIE to bacteria becoming resistant

Answer 4

Genetic variation: some bacteria in the population include mutation
Environmental change: antibiotics taken —> environment changes
Natural selection: bacteria with the resistant mutation gene are more likely to survive (better at coping with the change)
Inheritance: these bacteria reproduce causing the new generation to inherit the advantageous resistant mutation allele
Evolution: if the environment remains unchanged —> natural selection will occur over and over again —> new species evolved with all the individuals having the better adapted variation

Question 5

What are the factors that contribute to antibiotics being a problem in the future?

Answer 5

• antibiotics are too widely prescribed and used
• people do not complete courses of antibiotics —> makes it easier for resistance to develop
• some countries —> antibiotics are widely used in the food chain
• lack of hygiene encourages the spread of antibiotic resistant organisms

Question 6

How can we overcome the problems of resistance?

Answer 6

• reduce the use of antibiotics
• better educate people so they understand they do not always need antibiotics
• reduce the use of antibiotics in farm animals
• DNA sequencing will help to identify bacteria and find new ways of targeting them with drugs