Investigating the transmissibility of (W) in bifidobacteria exposed to acid and bile stress.

Transfer of antibiotic resistance genes from probiotic bacteria to pathogens poses a safety concern. Orally administered probiotics are exposed to stressful conditions during gastrointestinal transit. In this study, filter mating experiments were performed to investigate the potential role of exposure of isolates to acid and bile stress on the transfer of a tetracycline resistance gene, (W), to ATCC 51299. No transconjugants were obtained after mating with either stressed or unstressed , thereby suggesting that (W) could not be transferred as a result of exposure to gastrointestinal stresses.