Oral colonization by Lactobacillus reuteri ATCC 55730 after exposure to probiotics

Objective. The aim of this study was to investigate whether Lactobacillus reuteri ATCC 55730 can be detected in the oral cavity after discontinuation of administration of a product prepared with this bacterium. Materials and Methods. The study consisted of three 2-week periods: clearance period, intervention period, and post-treatment period. Twenty-five volunteers consumed a chewable tablet of L. reuteri ATCC 55730 (10(8) cfu/tablet) during a 14-day trial period. Saliva samples were collected and cultured onto MRS agar after a clearance period of 2 weeks and then daily after a 2-week intervention period for as long as L. reuteri was found. Lactobacillus reuteri colonies were analysed in saliva samples. The analysis was performed using selective media for L. reuteri followed by confirmation using the specific detection of reuterin produced by L. reuteri. Results. The number of L. reuteri carriers decreased gradually, and after 1 week only 8% of the subjects harboured the bacterium. After 5 weeks, L. reuteri was not detected in any of the subjects. Conclusion. Consuming L. reuteri for 2 weeks does not seem to be sufficient for permanent colonization of L. reuteri in the oral cavity.