Antibiotic resistance: causes and prevention

In a nutshell

Bacteria can become resistant to antibiotics. Antibiotic resistant bacteria pose a problem as there are no effective treatment for the infection and the antibiotic resistant strain (type) is able to easily spread between people as there is no existing immunity to these strains.

Antibiotic resistance is increasing

The problem is worsening as antibiotics are being overused and misused. This leads to 'superbugs' which are bacteria that are resistant to most known antibiotics that would treat a normal strain.

Example

MRSA is a relatively common 'superbug' that is very difficult to treat.

Evolution

Bacteria can become resistant to antibiotics through natural selection and evolution.

Biology; Inheritance, variation and evolution; KS4 Year 10; Antibiotic resistance: causes and prevention

1.	Variation in the bacterial population means some bacteria develop mutations in their DNA. These mutations may make them resistant to a particular antibiotic.
2.	Other bacteria in the population will not have this mutation so they will still be susceptible to antibiotics.
3.	Antibiotics are added to the population.
4.	The bacteria with the resistance gene survive the antibiotic treatment.
5.	The bacteria without the resistance gene do not survive the antibiotic treatment.
6.	This means that the resistant bacteria can reproduce more as they are not being killed. They will then pass on this resistance gene to their offspring. The antibiotic resistance gene will then become more common in the population over time. Evolution happens much faster in bacteria than other organisms as they reproduce more quickly.

Slowing antibiotic resistance

Method	Description
Only prescribe antibiotics when they are necessary	The overuse of antibiotics increases resistance so doctors should only prescribe antibiotics when they are necessary.
Complete the course of antibiotics	Patients should complete the course of antibiotics to ensure all of the bacteria have been killed and that there are none left that could mutate and develop into antibiotic resistant strains.
Only prescribe antibiotics for bacterial infections	Antibiotics do not kill viruses so they should not be prescribed for viral infections like the flu.
Farmers limiting antibiotic use	Farmers often give their animals antibiotics to prevent them getting ill and to make them grow more. However, this can lead to antibiotic resistance in the animals which can then spread to humans. So, farmers should limit their antibiotic use.

Making new antibiotics

Pharmaceutical companies are developing new antibiotics to kill these resistant strains. However, it is a very expensive process and the rate of development is very slow. This means that it is unlikely we can keep up with the demand for new antibiotics to fight the resistant strains.