A double-blind placebo-controlled trial to study therapeutic effects of probiotic Escherichia coli Nissle 1917 in subgroups of patients with irritable bowel syndrome.

PURPOSE: To study the therapeutic effects of probiotic Escherichia coli Nissle 1917 (EcN) in irritable bowel syndrome (IBS) and identify subgroups benefiting most. BACKGROUND: Some trials investigating therapeutic effects in irritable bowel syndrome have shown benefits in IBS subgroups only. Probiotic treatment seems to be promising. METHODS: Patients with irritable bowel syndrome (120; Rome II) were recruited to a prospective double-blind study and randomized to either EcN (n = 60) or placebo (n = 60) given for 12 weeks. Objectives were to describe efficacy and safety of EcN in different groups of irritable bowel syndrome. Outcome was assessed by 'Integrative Medicine Patient Satisfaction Scale'. RESULTS: Altogether, the responder rate was higher in the EcN than in the placebo group. However, only after 10 and 11 weeks, the differences were significant (Δ 20.0% points [95% CI 2.6; 37.4], p = 0.01 and Δ 18.3% points [95% CI 1.0; 35.7], p = 0.02, respectively). The best response was observed in the subgroup of patients with gastroenteritis or antibiotics prior to irritable bowel syndrome onset (Δ 45.7% points, p = 0.029). No significant differences were observed in any other subgroup. Both treatment groups showed similar adverse events and tolerance. CONCLUSIONS: Probiotic EcN shows effects in irritable bowel syndrome, especially in patients with altered enteric microflora, e.g. after gastroenterocolitis or administration of antibiotics.

Survival of the probiotic Escherichia coli Nissle 1917 (EcN) in the gastrointestinal tract given in combination with oral mesalamine to healthy volunteers.

BACKGROUND: Mesalamine and the probiotic E. coli Nissle 1917 (EcN) are both effective agents for the treatment of ulcerative colitis. A combined therapy may have more than additive efficacy. However, mesalamine may have antimicrobial effects on EcN. MATERIALS AND METHODS: In this prospective, randomized, double-blind, placebo-controlled study, 48 healthy volunteers took EcN in a run-in phase for 17 days (5-50 x 10(9) viable bacteria od). If stool samples became positive for EcN, volunteers received combination treatment with EcN plus either mesalamine (1500 mg twice a day) or placebo for 1 week. Fecal samples were further tested for EcN in 2- to 3-day intervals until a maximum of 48 weeks after treatment. Patient diaries, blood, and urine were checked to assess safety, compliance, and tolerance. RESULTS: During run-in, viable EcN were detected in 45 of the 48 volunteers (94%); 2 volunteers were positive before taking EcN. From days 1 to 7 of combination treatment (n = 40), the number of EcN-positive volunteers varied between 70% and 80% in the mesalamine group and between 85% and 95% in the placebo group. Differences between the groups were not significant (normal approximation: day 3, P > 0.15; day 5, P > 0.25; day 7, P > 0.076). At treatment discontinuation, 16 of 20 volunteers in the mesalamine group and 15 of 20 volunteers in the placebo group were EcN positive, whereas this figure dropped continuously up to week 12 after discontinuation (mesalamine, 7 of 20; placebo, 4 of 20). No differences between the groups were seen with regard to tolerance and safety. CONCLUSIONS: The combination of EcN and mesalamine has no significant effect on the survival of EcN in healthy volunteers.

The probiotic Escherichia coli strain Nissle 1917 interferes with invasion of human intestinal epithelial cells by different enteroinvasive bacterial pathogens.

The probiotic Escherichia coli strain Nissle 1917 (Mutaflor) of serotype O6:K5:H1 was reported to protect gnotobiotic piglets from infection with Salmonella enterica serovar Typhimurium. An important virulence property of Salmonella is invasion of host epithelial cells. Therefore, we tested for interference of E. coli strain Nissle 1917 with Salmonella invasion of INT407 cells. Simultaneous administration of E. coli strain Nissle 1917 and Salmonella resulted in up to 70% reduction of Salmonella invasion efficiency. Furthermore, invasion of Yersinia enterocolitica, Shigella flexneri, Legionella pneumophila and even of Listeria monocytogenes were inhibited by the probiotic E. coli strain Nissle 1917 without affecting the viability of the invasive bacteria. The observed inhibition of invasion was not due to the production of microcins by the Nissle 1917 strain because its isogenic microcin-negative mutant SK22D was as effective as the parent strain. Reduced invasion rates were also achieved if strain Nissle 1917 was separated from the invasive bacteria as well as from the INT407 monolayer by a membrane non-permeable for bacteria. We conclude E. coli Nissle 1917 to interfere with bacterial invasion of INT407 cells via a secreted component and not relying on direct physical contact with either the invasive bacteria or the epithelial cells.