Pathobiomes in Gut of Critically Ill Patients

Despite powerful antibiotics, 50% of the intestinal tracts of critically ill surgical patients are colonized by Pseudomonas aeruginosa, whose mere presence in this site increases mortality fourfold by mechanisms that remain unknown. Many patients who survive the initial surgical trauma still succumb to multi-organ failure and septicemia secondary to an invasive nosocomial infection. The sequelae of shock, hypoxia, and parental nutrition result in injury to the intestinal mucosa, changes in gut permeability, and failure of intestinal defense mechanisms. These conditions put patients at risk for infection and multiple organ failure secondary to the translocation of enteric bacteria, initiating a systemic release of inflammatory mediators-a process that has been termed gut-derived sepsis. Intestinal P. aeruginosa senses host factors released during stress and responds by activating its vir