Background & Aims: Escherichia coli Nissle 1917 (EcN) has been recommended as a therapeutic tool for ulcerative colitis (UC) treatment. However, to date, no meta-analysis has been performed on this topic.

Methods: We performed a literature search on PubMed, MEDLINE, Science Direct and EMBASE. We evaluated success rates for induction of remission, relapse rates and side effects, expressed as Intention-To-Treat. Odd ratios (OR), pooled OR and 95% confidence intervals (CI) were calculated, based on the Mantel-Haenszel method. Heterogeneity was assessed by using the χ2 and I2 statistics and, if present, a random-effects model was adopted.

Results: We selected six eligible trials, with 719 patients, 390 assigned to the study group and 329 to the control group. EcN induced remission in 61.6% of cases, while in the control group (mesalazine) the remission was achieved in 69.5% of cases, with a mean difference of 7.9%. The pooled OR was 0.92 (95% CI 0.15-9.66, p=0.93). A single study showed a better performance of EcN than the placebo. A relapse of the disease occurred in 36.8% in the EcN group and in 36.1% in the control group (mesalazine), with a mean difference of 0.8%, OR=1.07, with a 95% CI of 0.70-1.64 (p=0.74). Side effects were comparable (OR=1.44, 95% CI 0.80-2.59, p=0.22).

Conclusions: EcN is equivalent to mesalazine in preventing disease relapse, thus confirming current guideline recommendations. EcN seems to be as effective as controls in inducing remission and therefore, its use cannot be recommended as in one study the comparison was performed against placebo. Further studies may be helpful for this subject.

Abbreviations: EcN: Escherichia coli Nissle; UC: ulcerative colitis; IBD: inflammatory bowel disease; CD: Crohn’s disease; ITT: intention-to-treat.


ulcerative colitis, inflammatory bowel disease, probiotics, Escherichia coli Nissle, microbiota