How Quickly Do Bacteria Evolve? Lots Faster Than You Thought.
It has generally been assumed that bacteria evolve to overcome host defenses at a rate much slower than that of viruses. That assumption appears to be wrong. Helicobacter pylori, a cause of multiple cancers in humans, mutates at a rate similar to many viruses. See: "Microevolution of Helicobacter pylori During Prolonged Infection of Single Hosts and Within Families".
Just how fast can bacteria evolve? Would you be surprised to learn that within the lifetime of mice, bred to be free of gastrointestinal bacteria, bacteria from drinking water cannot only set up shop and colonize their hosts' guts but evolve into whole new species? If you are surprised, read: "Bacteria From Drinking Water Supply and Their Fate in Gastrointestinal Tracts of Germ-Free Mice: A Phylogenetic Comparison Study".
The long war continues, of course; and while we've been basking in our assumed victory over them for the last forty years our ancient enemies, descended from a long line of brilliant sappers, have been hard at work.
