Escherichia coli Nissle 1917 (Mutaflor): new insights into an old probiotic bacterium.

Probiotic bacteria are live microorganisms which contribute health benefits to their host. The numerous mechanisms of the probiotic-acting microorganisms include the induction of expression of certain cytokines and increasing the secretion of IgA and mucin. They activate lymphocytes and macrophages and inhibit the adhesion and invasion of epithelial cells. Escherichia coli Nissle 1917 (Mutaflor) is one of the most investigated probiotic bacteria. While the number of reports discussing the underlying mechanisms of Mutaflor has increased rapidly in recent years, novel clinical studies are missing. Here we provide an overview of the mechanisms of action and clinical studies related to Mutaflor. While most of the studies had positive outcomes, there are also a few in which Mutaflor did not perform to its expectations.