design: Each individual collected a fecal sample from which the total microbial DNA was extracted using the QIAamp DNA Stool Mini Kit (Qiagen, Hilden, Germany) following the manufacturers instructions, with a modication consisting of a bead-beating step with the lysis buffer (20 sec at 15 Hz). A fragment of the gene gyrase subunit B (gyrB) was amplified with primers F_La_334-354 (GGHGGAGGATAYAAGGTATCC) and R_La_816-836 (TRTANGAATCRTTRTGCTGC), and sequenced with Illumina MiSeq v3 600 with a 2x300bp PE format.