DNA was extracted from saliva pellets as described [34]. L. reuteri DSM 17938 and PTA 5289-specific PCR were identified using KAPA2G Robust HotStart PCR Ready Mix (2×) (Kapa Biosystems, Boston, MA, USA) and strain-specific primers [31]. Briefly, 2 µL of DNA extract was added to a total reaction volume of 25 µL (containing 12.5 µL of master mix and each primer pair at a concentration of 0.5 µM). PCR conditions were 95°C for 3 min; 40 cycles of 95°C for 15 s, 60°C for 15 s, and 72°C for 30 s; and 72°C for 5 min. PCR products were then verified by electrophoresis on 2% agarose gels allowed to run for 80 min at 120 V in 0.5× TBE (Tris/Borate/EDTA) buffer, pH 8.3, followed by ethidium bromide (0.2 µg/µL) staining.