Human immune signal sets off bacterial attack
A chemical secreted by immune cells when people are sick or stressed causes a common gut bacterium to go on the offensive against its host, according to a new study.
Pseudomonas aeruginosa lives harmlessly in the intestines of about 3 percent of healthy people. However, during and after major surgery, its presence can turn into a dangerous infection, says John Alverdy of the University of Chicago.
Scientists had previously proposed that such opportunistic infections develop when the immune system is weakened. Alverdy and his colleagues hypothesized that the microbes themselves may behave differently when they sense the body is stressed.