In bacteria, reproduction can be very fast, with a generation taking little more than a few minutes for some species. This short generation time, together with random mutations and the mechanisms of genetic recombination we saw in this article, allow bacteria (and other prokaryotes) to evolve very quickly.
Is that a good thing? It depends on your perspective. Rapid evolution means that bacteria can adapt to environmental changes, such as the introduction of an antibiotic, very quickly. That’s good for them—but bad for us, when we are the ones with the infection!