Colonies of Staphylococcus aureus

Bacteria can exchange genes with their neighbours, pick up DNA from their environment and, under the right conditions, produce offspring every 20 minutes. As we use penicillin and other antibiotics, the bacteria adapt to resist them. Once bacteria become resistant to medication, they are sometimes called 'superbugs'.

In this image we can compare two samples of one bacterium, called Staphylococcus aureus, which lives on our skin and up our nose. On the left you can see what happens when the bacteria are exposed to a disc of the antibiotic methicillin - the bacteria die off when they get close to the antibiotic. On the right the Staphylococcus had already been exposed to the methicillin and it was able to adapt, growing up to and on the disc of antibiotic. This adapted strain of bacterium is now methicillin-resistant Staphylococcus aureus, or MRSA. These bacteria are now more difficult to kill with antibiotics.