New observations and evidence to support the theory of evolution by natural selection continues to be found.
Repeated testing of a theory and finding more evidence to support it leads to the theory becoming more widely accepted amongst scientists.
Bacteria can evolve quickly because they reproduce at a fast rate. Mutations in the DNA of bacteria can produce new characteristics. A random mutation might cause some bacteria to become resistant to certain antibiotics, such as penicillin. Antibiotics usually kill bacteria, but in a case like this, the mutation means the bacteria cannot be destroyed by the antibiotic. The development of antibiotic resistance in bacteria gives more evidence to support the theory of natural selection leading to evolution.
The main steps in the development of resistance are:
The number of resistant strains has increased, partly due to the misuse of antibiotics. This has resulted in more infections that are difficult to control.
MRSA is methicillin-resistant Staphylococcus aureus. It is a very dangerous type of bacteria because it is resistant to most antibiotics, so if someone gets infected with MRSA they cannot be treated easily.