Composition of gut microbial communities of Colombian children with or without Blastocystis colonization. Gut microbial communities in Colombian children

Blastocystis is a protist that lives in the intestinal tract of a variety of hosts, including humans. It is still unclear how Blastocystis causes disease, which presents an ongoing challenge for researchers. Despite the controversial findings on the association between Blastocystis and clinical digestive manifestations, there is currently no consensus as to whether this protozoan actually behaves as a pathogen in humans. Furthermore, the relationship between Blastocystis and the intestinal microbiota composition is not yet clear. For that reason, the aim of this study was to identify if colonization by Blastocystis and its subtypes (STs) is related to changes in the diversity and relative abundance of bacterial communities, compared with those of Blastocystis-free individuals, using molecular characterization in the Colombian human population. We took stool samples from 57 school-age children attending a daycare institution in Popayán (Southwest Colombia). Whole DNA was extracted and examined by 16S-rRNA amplicon-based sequencing. We evaluated how Blastocystis and its STs are associated with host variables and the diversity and abundance of microbial communities. There was greater microbial richness in the intestines of children colonized by Blastocystis, which could, therefore, be considered a benefit to intestinal health. The phylum Firmicutes was the predominant taxonomic unit in all the groups analyzed. In Blastocystis-free individuals, there was an increase in the proportion of Bacteroidetes; similarly, in children colonized by Blastocystis, there was a greater relative abundance of the phylum Proteobacteria. We observed that children with ST1 and ST2 presented a higher relative abundance of Bacteroides compared with those with ST3, who showed an increased proportion of Proteobacteria. There was a potential relationship between the presence of this protozoan, a decrease in Bacteroides, and an increase in the relative abundance of the Faecalibacterium genus. It was also evident that the presence of Blastocystis was unrelated to dysbiosis at the intestinal level; on the contrary, its presence can be linked to a “normal” or “healthy” microbiota, and it possibly plays a role in the ecology of the intestinal microbiota through its interaction with other microbial components.