Determinación del microbioma intestinal en pacientes con infección por clostridioides difficile adquirida en unidad de cuidados intensivos y comunidad
Thesis
Clostridioides difficile (CD) is the main cause of antibiotic-associated diarrhea, associated with dysregulation of the host intestinal microbiota. This dysregulation affects the different components of the microbiota, with the bacterial component being the most widely studied. However, other groups of organisms, such as viruses and eukaryotes, have also been described as fundamental members of the intestinal ecosystem. Additionally, the function of clinically important loci, especially those associated with antibiotic resistance, has been highlighted. Despite the great relevance of the members of the intestinal microbiota in maintaining the homeostasis of the intestinal ecosystem, little is known about their role in the field of CDI. Furthermore, the influence of the acquisition site of diarrhea on the composition (diversity and abundance) of the microbiome, especially in the context of inflammatory bowel diseases, is poorly understood. Therefore, this study aims to determine the intestinal microbiome composition in patients with diarrhea associated with CDI, acquired in the Intensive Care Unit (ICU) and in the community, by implementing high-throughput sequencing techniques. To achieve this, 98 DNA samples from patients with community-acquired and hospital-acquired diarrhea, both positive and negative for CDI, were selected and subjected to 16S rRNA and 18S rRNA single marker sequencing. Subsequently, 48 samples were chosen from this initial pool and subjected to metagenomic sequencing. Initially, we observed changes in the microbiota composition of the groups with hospital-acquired diarrhea (HCFO/+, HCFO/-) characterized by a decrease in beneficial microorganisms, suggesting the importance of the place of acquisition of the infection in the modulation of the intestinal ecosystem. Similarly, we observed interactions between the different members of the intestinal microbiota. The metagenomic sequencing revealed 51 differentially abundant species between the study groups, with a reduction of the genes involved in the butyrate metabolism in the groups of patients with hospital-acquired diarrhea. Finally, we observed distinctive acetate and butyrate-producing microorganisms for each group, with marked differences in their abundances and resistance profiles. The role of microorganisms associated with butyrate metabolism on the intestinal ecosystem in the CDI scenario is also emphasized. On the other hand, the study of tick microbiota has become a useful tool in the surveillance and control of tick-borne diseases, which are widely distributed in the European continent and pose a significant public health problem. This is particularly true in Spain, where regions such as Castilla y León have reported increasing trends in tick populations and bites. Therefore, using the single marker deep sequencing analysis scheme generated in the previous sections, we described the microbiota of 29 specimens of 5 species of hard ticks collected in that region. We found differences in the taxonomic composition as well as in the correlations between the members of their microbiota. This pilot study is the first of its kind carried out in that territory.
