Dysbiosis of intestinal microbiota in critically ill patients and risk of in-hospital mortality.

BACKGROUND Despite the essential functions of the intestinal microbiota in human physiology, little research was reported on gut microbiota alterations in intensive care patients. This investigation examined the dysbacteriosis of intestinal flora in critically ill patients and evaluated the prognostic performance of this dysbiosis to predict in-hospital mortality. METHODS A prospective cohort of patients were consecutively recruited in the Intensive Care Units (ICUs) in Guangdong Provincial People's Hospital from March 2017 through October 2017. Acute Physiology and Chronic Health Evaluation (APACHE) II score and Sequential Organ Failure Assessment (SOFA) score were assessed, and fecal samples were taken for examination within 24 hours of ICU admission. The taxonomic composition of the intestinal microbiome was determined using 16S rDNA gene sequencing. Patients were divided into survival and death groups based on hospital outcomes. The two groups were statistically compared using the Wilcoxon test and Metastats analysis. The genera of bacteria showing significantly different abundance between groups were assessed as predictors of in-hospital death. The prognostic value of bacterial abundance alone and in combination with APACHE II or SOFA score was evaluated using the area under the receiver operating characteristic curve (AUROC). RESULTS Among the 61 patients examined, 12 patients (19.7%) died during their hospital stay. Bifidobacterium abundance was higher in the survival group than the death group (P = 0.031). The AUROC of Bifidobacterium abundance in identifying in-hospital death at a cut-off probability of 0.0041 was 0.718 (95% confidence interval [CI], 0.588-0.826). The panel of Bifidobacterium abundance plus SOFA (AUROC, 0.882; 95% CI, 0.774-0.950) outperformed SOFA (AUROC, 0.649; 95% CI, 0.516-0.767; P = 0.012) and Bifidobacterium abundance alone (P = 0.007). The panel of Bifidobacterium abundance plus APACHE II (AUROC, 0.876; 95% CI, 0.766-0.946) outperformed APACHE II (AUROC, 0.724; 95% CI, 0.595-0.831; P = 0.035) and Bifidobacterium abundance alone (P = 0.012). CONCLUSIONS Dysbiosis of intestinal microbiota with variable degrees of reduction in Bifidobacterium abundance exhibited promising performance in the predicting of in-hospital mortality and provides incremental prognostic value to existing scoring systems in the adult intensive care unit (ICU) setting.