Comparative metagenomic analysis of diarrheal and non-diarrheal gut microbiome delineating the identification of prospective prognostic markers and probiotics to protect from diarrhea: a brief report

Introduction Diarrhea is a leading contributor of mortality globally. To mitigate its disease burden, improved prognosis and alternative therapeutic approaches must be deployed. A cross-sectional gut microbiome analysis of 23 non-diarrheal and 5 diarrheal fecal samples was conducted with the aim of meeting the WHO’s GAPPD (Global Action Plan for Pneumonia and Diarrhea) goals. Hypothesis Next-generation sequencing is a potent tool being increasingly used for epidemiological surveillance. It can help in the comparison of the structural diversity of the gut microbiome between diarrheal and non-diarrheal samples, thereby aiding in the identification of prospective prognostic and therapeutic candidates. Aim The pilot study was designed to identify prospective taxa that were comparatively enriched in non-diarrheal samples and to predict gut microbial community interactions. Methodology 16S rRNA amplicon sequencing and subsequent analysis were undertaken for taxonomic profiling and abundance interpretation of OTUs. Results Significant differences between the two groups with respect to structural composition was revealed. Firmicutes was the most abundant phylum in the majority of the samples. The B/F ratio was consistently <1 in all diarrheal samples. A significant difference in the mean B/F ratio of the two groups was found. Proteobacteria was significantly more abundant in the diarrheal group. On the other hand, Prevotellaceae was the most abundant family in non-diarrheal samples and was suppressed significantly in diarrheal samples. Streptococcaceae was the most abundant family in 60% of diarrheal samples; where Streptococcaceae was suppressed, Bacteroideaceae and Nocardiaceae were the most abundant. In non-diarrheal samples, where Streptococcaceae was almost completely suppressed, Bifidobacteriaceae was the most abundant and significantly suppressed other families. A negative correlation was observed between Prevotellaceae and Bacteroideaceae in the non-diarrheal group. Prevotella copri was the most abundant species in 70% of non-diarrheal samples and was significantly suppressed in diarrheal samples. Proteus mirabilis was identified in all the non-diarrheal samples, while they were absent in diarrheal samples. Conclusion The OTUs associated with diarrheal dysbiosis can serve as prognostic markers. To our knowledge, this is the first report on the comparative analysis of diarrheal and non-diarrheal microbiome, distinctly addressing the gut microbiome dysbiosis from the context that can lead to the development of prognostic markers and probiotics to protect the endemic population from diarrhea and help in achieving Sustainable Development Goals 2 and 3.