Figure 1. Proposed interactome between the intestinal microbiome versus pathobiome and the immune system.

The often unavoidable transition of the normal gut microbiome to a pathobiome during the course of critical illness has the potential to subvert the immune system when pathogens activate their virulence and express quorum sensing signaling molecules that lead to pathoadaptive inflammation. A major hypothesis to test is whether maintaining the intestinal microbiota through the course of critical illness will more appropriately direct the immune response toward recovery and accelerate organ recovery.

Pi= phosphate, PRR= pathogen recognition molecule, PAMP= pathogen associated molecular pattern.