Last month brought fresh evidence that while small, bacteria can certainly look out for themselves. Clostridium difficile, a microbe that can cause serious digestive illness and death in vulnerable patients in hospitals and nursing homes but rarely bothers healthy adults outside healthcare settings, was blamed by the federal Centers for Disease Control and Prevention for doing just that in four states. Like many other germs, it apparently had mutated, under pressure from antibiotics, into a toxic new strain. ~snip~ Military service members injured in Iraq and Afghanistan increasingly are coming home with Acinetobacter baumannii, a potent microbe that causes pneumonia...