Gut dysbiosis and its treatment in patients with critical illness.

The gut is a target organ that functions as the "motor" of critical illness. In patients with critical illness, the disrupted gut microbiota following infection and injury could cause diarrhea, pneumonia, and systemic inflammation. For maintaining the gut microbiota, therapeutic approaches are required to modulate host responses and prevent systemic inflammation. Probiotics and synbiotics could maintain the gut microbiota and decrease not only the incidence of diarrhea but also that of ventilator-associated pneumonia. The effects of probiotics/synbiotics differ with the type of bacteria and disease severity. Adverse effects of probiotics have been reported; therefore, the selection of safe and effective probiotics/synbiotics is warranted. Refractory diarrhea with prolonged dysbiosis may require a novel intestinal therapy, such as fecal microbiota transplantation, to alleviate gut dysbiosis.