Effects of exogenous probiotics on the gut microbiota and clinical outcomes in critically ill patients: a randomized controlled trial

BACKGROUND Gut microbiota play an important role in the inflammation. This study aimed to investigate whether exogenous probiotics could improve the intestinal barrier function effect via attenuating inflammation and immunomodulation to improve the clinical outcomes in critically ill patients. METHODS A single-blind, randomized controlled trial was performed in a respiratory intensive care unit (RICUs). Patients assigned to the intervention group received probiotics Clostridium butyricum until death or discharge. Stool and blood samples were collected on the 1st day and 15th day of administration. Primary clinical outcomes and clinical manifestations were recorded during the follow-up period. RESULTS There were 61 patients in this study, with 28 patients receiving probiotics. There were no differences in the mortality and hospital stay between intervention group and control group. In addition, the duration of fever (% of hospital stays) was significantly shorter in the intervention group as compared to control group (4.85% vs. 12.94%, P=0.00). The incidence of constipation significantly reduced in the intervention group (17.86% vs. 42.42%, P=0.04). The overall ratio of gastrointestinal adverse effects was comparable between them. Bactericides significantly decreased after probiotic intervention (Δm=-0.69, P=0.048), while Escherichia coli and Enterococcus tended to decrease in the intervention group (Δm=-0.65, P=0.08; Δm=-0.52, P=0.22) on the day 15. No fluctuation was observed in the Bifidobacterium and Lactobacillus after probiotic intervention. CONCLUSIONS Our study fails to show the beneficial effects of probiotics on the primary clinical outcomes in critically ill patients. The intestinal barrier is damaged, and probiotics may reduce the burden of Gm-bacteria from the gut.