This was an open study with the objective to study the colonisation of the colon by Lactobacillus reuteri ATCC 55730, in ten adult patients undergoing a colonoscopy examination.

Lactobacillus reuteri was ingested at a dosage of 10^9 CFU/day, as yoghurt (5 patients) or as probiotic fruit juice (5 patients) for 12 days before the colonoscopy. Faecal samples were analysed before and after 12 days of consumption of the probiotic foods. Biopsies from all three parts of the colon were sampled on day 12. Identification methods for Lactobacillus reuteri were based on biochemical properties and a gene-based method (RiboPrint system). No subject was colonised with Lactobacillus reuteri before the start of the study.

Live Lactobacillus reuteri cells were found on day 12 in faecal samples from 3/5 subjects in the yoghurt group and in all five in the juice group. Lactobacillus reuteri was identified at the strain level in the colon biopsies from one subject.

Conclusion: The daily consumption of Lactobacillus reuteri in yoghurt or fruit juice for 12 days resulted in successful colonisation of 80% of the study subjects, measured as live bacteria cells in faecal samples. One of the subjects also had the administered Lactobacillus reuteri strain cultivated from the colon biopsies.