Analysis of intestinal flora and inflammatory cytokine levels in children with non-infectious diarrhea

BACKGROUND: Non-infectious diarrhea is a common symptom in infants and young children. We aimed to analyze the intestinal flora and serum inflammatory cytokine levels of children with non-infectious diarrhea. METHODS: Eighty-nine children with non-infectious diarrhea and 76 healthy children were enrolled from the First Affiliated Hospital of Hainan Medical University between February 2017 and June 2020. Fecal bacterial samples were collected in sterile containers. Following serial dilution, the bacterial samples were cultured in an aerobic medium to cultivate Escherichia coli (E. coli), Enterococci, Lactobacilli, and Bifidobacteria. The levels of inflammatory cytokines in the serum, including interleukin (IL)-2, IL-8, IL-10, and tumor necrosis factor-alpha (TNF-α), were determined by enzyme-linked immunosorbent assay. Results between the groups were compared using the paired t-test. The chi-square test was employed to analyze categorical data, with analysis of variance used for multiple-group comparisons. RESULTS: No significant differences were observed between the diarrhea and control groups in terms of sex, age, or body mass index distribution. Compared to the control group, the diarrhea group had significantly elevated levels of E. coli and Enterococci but significantly decreased levels of Bifidobacteria and Lactobacilli. In terms of inflammatory cytokines, the levels of IL-2, IL-8, IL-10, and TNF-α were significantly higher in the diarrhea group than in the control group (all P<0.05). In children with non-infectious diarrhea, the levels of IL-2, IL-8, IL-10, and TNF-α were positively correlated with the amount of E. coli (r values of 0.412, 0.381, 0.479, and 0.216, respectively) and Enterococci (r values of 0.257, 0.336, 0.357, and 0.328). Further, the amount of Lactobacilli was positively correlated with IL-2 and IL-10 levels (r values of 0.342 and 0.438, respectively), and that of Bifidobacteria was negatively correlated with IL-2, IL-8, IL-10, and TNF-α levels (r values of −0.252, −0.336, −0.328, and −0.293, respectively). Finally, the level of Lactobacilli was also negatively correlated with IL-8 and TNF-α levels (r values −0.301 and −0.464, respectively; both P<0.05). CONCLUSIONS: The abundance and abnormality of E. coli, Enterococci, Lactobacilli, and Bifidobacteria in the intestinal flora of children with non-infectious diarrhea are associated with increased levels of IL-2, IL-8, IL-10, and TNF-α.