Researchers at the University of Chicago found that after a long stay in the Intensive Care Unit (ICU) only a handful of pathogenic microbe species remain behind in patients’ intestines. The team tested these remaining pathogens and discovered that some can become deadly when provoked by conditions that mimic the body’s stress response to illness. “They’ve got a lot of bad guys in there, but the presence of bad guys alone doesn’t tell you who’s going to live or die,” says John Alverdy, a gastrointestinal surgeon and one of two senior authors on the study. “It’s not only which microbes are there, but how they behave when provoked by the harsh and hostile conditions of critical illness.” By John Alverdy et al, published in mBio®, journal of the American Society for Microbiology.