title: Structural and functional changes in the gut microbiota associated to Clostridium difficile infection.
abstract: Antibiotic therapy is a causative agent of severe disturbances in microbial communities. In healthy individuals, the gut microbiota prevents infection by harmful microorganisms through direct inhibition (releasing antimicrobial compounds), competition, or stimulation of the host's immune defenses. However, widespread antibiotic use has resulted in short- and long-term shifts in the gut microbiota structure, leading to a loss in colonization resistance in some cases. Consequently, some patients develop Clostridium difficile infection (CDI) after taking an antibiotic (AB) and, at present, this opportunistic pathogen is one of the main causes of antibiotic-associated diarrhea in hospitalized patients. Here, we analyze the composition and functional differences in the gut microbiota of C. difficile infected (CDI) vs. non-infected patients, both patient groups having been treated with AB therapy. To do so we used 16S rRNA gene and metagenomic 454-based pyrosequencing approaches. Samples were taken before, during and after AB treatment and were checked for the presence of the pathogen. We performed different analyses and comparisons between infected (CD+) vs. non-infected (CD-) samples, allowing proposing putative candidate taxa and functions that might protect against C. difficile colonization. Most of these potentially protective taxa belonged to the Firmicutes phylum, mainly to the order Clostridiales, while some candidate protective functions were related to aromatic amino acid biosynthesis and stress response mechanisms. We also found that CDI patients showed, in general, lower diversity and richness than non-infected, as well as an overrepresentation of members of the families Bacteroidaceae, Enterococcaceae, Lactobacillaceae and Clostridium clusters XI and XIVa. Regarding metabolic functions, we detected higher abundance of genes involved in the transport and binding of carbohydrates, ions, and others compounds as a response to an antibiotic environment.
authors.affiliation: Unidad Mixta de Investigación en Genómica y Salud de la Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO) y el Instituto Cavanilles de Biodiversidad y Biología Evolutiva de la Universitat de València València, Spain ; CIBER en Epidemiología y Salud Pública Madrid, Spain.
authors.forename: Ana E
authors.initials: AE
authors.lastname: Pérez-Cobas
authors.affiliation: Unidad Mixta de Investigación en Genómica y Salud de la Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO) y el Instituto Cavanilles de Biodiversidad y Biología Evolutiva de la Universitat de València València, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Artacho
authors.affiliation: Institute for Clinical Molecular Biology, Christian-Albrechts-University Kiel, Germany ; Department for Internal Medicine, University Hospital Schleswig-Holstein Kiel, Germany.
authors.forename: Stephan J
authors.initials: SJ
authors.lastname: Ott
authors.affiliation: Unidad Mixta de Investigación en Genómica y Salud de la Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO) y el Instituto Cavanilles de Biodiversidad y Biología Evolutiva de la Universitat de València València, Spain ; CIBER en Epidemiología y Salud Pública Madrid, Spain.
authors.forename: Andrés
authors.initials: A
authors.lastname: Moya
authors.affiliation: Unidad Mixta de Investigación en Genómica y Salud de la Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO) y el Instituto Cavanilles de Biodiversidad y Biología Evolutiva de la Universitat de València València, Spain ; CIBER en Epidemiología y Salud Pública Madrid, Spain.
authors.forename: María J
authors.initials: MJ
authors.lastname: Gosalbes
authors.affiliation: Unidad Mixta de Investigación en Genómica y Salud de la Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO) y el Instituto Cavanilles de Biodiversidad y Biología Evolutiva de la Universitat de València València, Spain ; CIBER en Epidemiología y Salud Pública Madrid, Spain.
authors.forename: Amparo
authors.initials: A
authors.lastname: Latorre
keywords: C. difficile infection; Gut microbiota; bacterial composition; colonization resistance; metabolic functions