Fecal DNA Isolation and Quantification

DNA from fecal samples collected at the end of the intervention was isolated as previously described (32 (link)) with some minor modifications. The samples were initially mixed with 250 μL lysis buffer (Agowa, Berlin, Germany), 250 μL zirconium beads (0.1 mm), and 200 μL phenol, before being introduced to a BeadBeater (BioSpec Products, Bartlesville, OK, USA) for two × 2 min. Quantitative PCR detection was performed with the primers and according to conditions described previously (33 ). To evaluate if samples contained F19, data were plotted from low to high Ct, resulting in an S-shaped curve, with true positives in the lower and true negatives in the higher end, as previously described (33 ).