|Bacterial mutations breaking through and competing with each other|
A fascinating experiment showing anti-biotic resistance develop over a few days. On a large dish you can actually see mutations break through the next barrier as the bacteria evolves.
Similar to what can happen with the HIV virus if medications aren't taken correctly. The HIV virus can get to a large enough level in the bloodstream to where mutations against the medication will occur and you can end up with an HIV virus resistant to many of the more common treatments. This is why they tell us to take the pills every day at the same time, so the virus doesn't get a chance to build up.
For those that may not be aware, in the HIV world "undetectable" means the HIV virus is at such a low level in the blood that current methods can't detect it. The pills keep it that way if taken properly. One doctor explained it to me that it was like tying a rag around a dripping pipe. Each day you have to replace the rag or it'll start dripping.
Video of the experiment is here; NPR Health News.