Department of Clinical Medicine and Surgery, Division of Gastroenterology, University of Naples "Federico II", Naples, Italy. Istituto di Ricovero e Cura a Carattere Scientifico - Ricerca Diagnostica e Nucleare (IRCCS-SDN), Naples, Italy. Fresystem SpA-Caivano, Naples, Italy. Department of Agricultural Sciences, Division of Microbiology, University of Naples "Federico II" - Portici, Naples, Italy. Task Force on Microbiome Studies, University of Naples "Federico II", Naples, Italy.