Escherichia coli Nissle 1917, often referred to as EcN, is a unique and well-investigated strain within the diverse E. coli family. Unlike many of its relatives commonly associated with disease, EcN is recognized for its beneficial properties and is utilized as a probiotic. Its discovery traces back to 1917, when German physician Alfred Nissle isolated it from a soldier who remained healthy during a severe outbreak of shigellosis, a type of diarrheal illness. This history highlights its surprising nature as a health-promoting bacterium.
What Makes Escherichia coli Nissle Special
EcN differs from pathogenic E. coli strains due to several characteristics. It is classified as a non-pathogenic, commensal, and probiotic bacterium, meaning it naturally resides in the human gut without causing illness and offers health benefits. It lacks virulence factors, such as pathogenic adhesion factors, enterotoxins, or cytotoxins, typically found in harmful E. coli strains. EcN also demonstrates rapid elimination by the non-specific defense factors present in blood serum.
EcN possesses specialized structures, including F1C and Curli fimbriae, which enable it to adhere to the intestinal lining and form biofilms, promoting gut colonization. EcN produces siderophores, compounds that aid in iron acquisition. It also belongs to the O6 serotype, a feature sometimes found in extra-intestinal pathogenic E. coli but without associated virulence. Its genetic makeup includes specific genomic islands with gene clusters for “fitness factors,” contributing to its probiotic activities. EcN’s ability to resist certain bacteriophages also helps maintain its presence in the gut.
How Escherichia coli Nissle Supports Gut Health
EcN contributes to gut health through a variety of mechanisms that interact with the host and the resident microbiota. It strengthens the gut barrier function, which is the protective lining of the intestines that prevents harmful substances from entering the bloodstream. EcN can also modulate the immune system, influencing the production of various immune factors and promoting beneficial immunological responses. This interaction helps optimize gut health and can reduce inflammation.
The probiotic competes directly with pathogenic bacteria for nutrients and adhesion sites in the intestinal tract. EcN achieves this by producing antimicrobial compounds, such as microcins, which inhibit the growth of harmful bacteria like Salmonella and Shiga toxin-producing E. coli. EcN also influences the composition of the gut microbiota, helping to maintain a balanced microbial community. It contributes to the production of beneficial metabolites, including short-chain fatty acids (SCFAs) like butyrate and valerate, which are important for colon cell health and can reduce inflammation.
Applications and Benefits of Escherichia coli Nissle
EcN is used in managing various gastrointestinal conditions. It has shown promise in supporting individuals with inflammatory bowel disease (IBD), particularly ulcerative colitis. Clinical studies, including a large randomized trial, have indicated that EcN can be comparable to certain conventional therapies, such as mesalazine, in maintaining remission in ulcerative colitis patients. This suggests its potential as an alternative or supplementary treatment for this chronic inflammatory condition.
The probiotic has also been explored for managing irritable bowel syndrome (IBS) symptoms and preventing certain types of diarrhea. EcN has been studied for its efficacy in reducing the duration and severity of acute diarrhea in infants and toddlers. Its use extends to potentially preventing antibiotic-associated diarrhea and traveler’s diarrhea, by helping to stabilize the gut microbiota disrupted by antibiotics or exposure to new pathogens.
Safety and Considerations
Escherichia coli Nissle 1917 generally has a favorable safety profile, making it well-tolerated for many individuals. Common side effects, if they occur, are typically mild and transient, including bloating, abdominal pain, or gas. These minor digestive disturbances often subside as the gut microbiota adjusts to the presence of the probiotic.
Despite its overall safety, considerations and contraindications exist. Individuals with compromised immune systems, such as those undergoing immunosuppressive therapy, should use EcN with caution and under medical supervision. Those with short bowel syndrome or other severe medical conditions may require assessment before using this probiotic. While rare, hypersensitive reactions like rashes have been reported. It is advisable to consult a healthcare professional before initiating EcN, especially for specific health conditions or if taking other medications, as some antibiotics may reduce its effectiveness.