Background/aims: Lactobacillus rhamnosus GG (LGG) is one of the most widely studied probiotic bacterial strain. The benefits of LGG treatment in gastrointestinal disorders are well documented. The aim of the present study was to investigate whether LGG can be detected in the oral cavity after discontinuation of administration of a product prepared with this bacterium.
Material and methods: 56 volunteers consumed Gefilus juice (Valio Ltd, Helsinki, Finland) containing LGG during a 14-day trial period. Saliva samples were collected and cultured onto MRS agar after a clearance period and then daily after a 2-week intervention period for as long as LGG was found. LGG-like colonies were analyzed in saliva samples, identified by characteristic colony morphology, a lactose fermentation test, and PCR with specific primers.
Results: LGG was not able to colonize the oral cavity. It could only be temporarily detected. In one female subject, however, whose medical history revealed use of LGG in childhood, the bacterium was detected in all saliva samples taken up to 5 months. (She was excluded from the intervention trial).
Conclusion: Permanent colonization of LGG in the oral cavity is improbable but seems possible in individual cases.