For the last decade or so, bacteria that are immune to the effects of antibiotics have been a persistent and growing threat in medicine. Ultimately, the problem goes back to the antibiotic not being administered long enough to kill off the entire colony. The few survivors that managed to make it through the increasing toxicity of their environment because they either had a gene which rendered them immune (and the toxins released when the other bacteria died weren't enough to poison them) or assembled one and survived long enough to breed and pass the gene along to other bacteria. This …