Probiotic <i>Lactobacillus casei</i>: Effective for Managing Childhood Diarrhea by Altering Gut Microbiota and Attenuating Fecal Inflammatory Markers

Background: Acute diarrhea is a major cause of childhood morbidity and an economic burden for families. The aim of this study is to explore the effect of probiotics on clinical symptoms, intestinal microbiota, and inflammatory markers during childhood diarrhea. Methods: Children (n = 81) aged six months to six years (mean age 2.31 years) hospitalized for acute diarrhea were randomized to receive probiotics (Lactobacillus casei variety rhamnosus; n = 42) or no probiotics (n = 39) orally twice daily for seven days. Feces samples were also collected to evaluate microbial content using a traditional agar plate and next-generation sequencing. Immunoglobulin A (IgA), lactoferrin, and calprotectin were determined by enzyme-linked immunosorbent assay (ELISA) and compared in different groups. Other clinical symptoms or signs, including fever, vomiting, diarrhea, abdominal pain, bloated abdomen, daily intake, appetite, and body weight were also assessed. Results: Data were collected from 81 individuals across three different time points. Total fecal IgA levels in fecal extracts of the probiotics group were higher than those in the control group, reaching statistical significance (p &lt; 0.05). Concentrations of fecal lactoferrin and calprotectin were significantly downregulated in patients with probiotic Lactobacillus casei variety rhamnosus (Lc) consumption compared to those of the control (p &lt; 0.05). Probiotic Lc administration may be beneficial for gut-microbiota modulation, as shown by the data collected at one week after enrollment. Counts of Bifidobacteria and Lactobacillus species were elevated in stool culture of the probiotic group. Appetite and oral intake, body-weight gain, abdominal pain, bloating, as well as bowel habits (diarrhea) were much better in children receiving probiotics compared with those in the control group. Conclusion: Fecal IgA increased during acute diarrhea under Lc treatment; in contrast, fecal lactoferrin and calprotectin were downregulated during acute diarrhea under Lc treatment. Probiotic Lc may be a useful supplement for application in children during acute diarrhea to reduce clinical severity and intestinal inflammatory reaction