Are probiotics detectable in human feces after oral uptake by healthy volunteers

GOALS: Assessment of the presence of probiotic bacteria in feces after oral ingestion. BACKGROUND: Probiotic bacteria are said to have beneficial effects on the host. As a precondition for any effect, probiotic strains must survive passage through the gastrointestinal tract. STUDY: The feces of seven volunteers were analyzed for the presence of probiotic strains after one week's oral ingestion of each of six commercially available products: E. coli Nissle 0.5–5 × 109 cells (Mutaflor®), Enterococcus faecium SF 68 7.5 × 107 cells (Bioflorin®), Lactobacillus acidophilus and Bifidobacterium infantis both 1 × 109 cells (Infloran®), Lactobacillus gasseri and Bifidobacterium longum both 1 × 108 cells (Omniflora®), Lactobacillus casei rhamnosus 1 × 109 cells (Antibiophilus®), and yoghurt enriched with Lactobacillus casei Immunitas 1 × 1010 cells (Actimel®). Ten colonies were selected from each stool sample, and DNA was extracted and typed using random amplification of polymorphic DNA (RAPD). Typing patterns of the ingested probiotics and the fecal isolates were compared. RESULTS: Fingerprints identical to the ingested probiotic strains were recovered from fecal samples of 4/7 volunteers after one week of Mutaflor®, from 4/6 after taking Bioflorin®, and from 1/6 after Infloran®. Cultivation of strains of the same species from fecal specimens was negative after consumption of Antibiophilus®, Omniflora® and Actimel®. CONCLUSIONS: After oral consumption of probiotics, E. coli and enterococci could be detected in stool samples (57% and 67%, respectively). In contrast, with only one exception, ingested lactobacilli and bifidobacteria could not be detected in human feces.