You might know of E. coli as a scary bacterium that causes all sorts of diseases, and in some cases you might be right. But, there is more to this bacterium than meets the eye: did you know that most strains are harmless, live normally in the human gut, and some also possess probiotic properties? Read on to find out more about the intriguing E. coli strains that have been used for the benefit of our gut health.

By Asha Zaharudin

The infamous Escherichia coli is perhaps most famously associated with serious food poisoning, especially from raw or uncooked meat products or contaminated vegetables. The vast majority of E. coli strains, however, are usually harmless and commonly inhabit the lower intestine as part of our normal gut microbiome. Surprisingly, there are also probiotic strains of E. coli that have been discovered around a century ago, which have been extensively used to treat a range of intestinal disorders.

A brief history of probiotic E. coli

Commensal E. coli are known to be present in a human gut, albeit in relatively low numbers compared to representative species from the Bacteroides and Firmicutes phyla. Whether they contribute significantly to normal gut function also remains to be investigated1. Nevertheless, E. coli strains are key players in at least three commercially available probiotic products, Mutaflor, Symbioflor 2, and Colinfant, all of which have been extensively studied in multiple scientific investigations1. Of the three products, most is known about the prevalent strain in Mutaflor, called E. coli Nissle 1917 (or EcN, for short).

Since its discovery, EcN was able to combat infections and treat patients suffering from gastrointestinal diseases.

EcN is probably the most intensively studied bacterial strain. It was said to be isolated a century ago from the intestinal microbiota of a First World War solider by Alfred Nissle, who discovered that these isolated E. coli strains were able to stop the growth of pathogenic bacteria in Petri dishes. He eventually showed that EcN was able to combat infections and treat patients suffering from gastrointestinal diseases2

E. coli from the gut, for the gut

Since its discovery, EcN has largely been used within the treatment of inflammatory bowel disease (IBD), with the earliest published study dating back to 19893. This probiotic strain is usually administered as Mutaflor, a biotherapeutic product originated from Nissle in the early 20th century and currently still in production by the German pharmaceutical company Ardeypharm GmbH1. Ulcerative colitis (UC), a form of IBD in which the colon lining is especially affected, can also be treated with EcN. Many studies show EcN to be as safe and effective at maintaining remission of UC, achieving results that are comparable to the standard mesalazine medication4. EcN has also been successful in treating acute diarrhea in infants and toddlers, while a study noted that its administration was safe, well-tolerated, and also improved their general state of health5. It should also be noted, however, that EcN is not recommended for the treatment of Crohn’s disease (CD), another variant of IBD, as it is related to adherent-invasive E. coli (AIEC) colonization. Thus, any E. coli-containing probiotic are rarely tested, and unlikely to be effective to treat CD1.

E. coli: not your average probiotic

Though the term probiotics is usually synonymous with food products containing e.g. lactic acid bacteria, E. coli probiotics are unlikely to hit your supermarket shelves any time soon. Unlike probiotic products such as fermented foods, E. coli probiotics are intended for use in the treatment of disease instead of retaining health and well-being and reducing risk of such diseases. This strain has endured a century’s worth of investigation, and now more research is being done to unveil more details about some of E. coli’s probiotic properties. Though this form of medicine became out of fashion as antibiotics gained popularity, a revival of these past treatment methods (i.e. probiotics) is slowly gaining traction as fears of antibiotic resistance persist.
References:
  1. Wassenaar T. M. (2016). Insights from 100 Years of Research with Probiotic  ColiEuropean journal of microbiology & immunology6(3), 147–161. doi:10.1556/1886.2016.00029
  2. Sonnenborn U. (2106).  Escherichia colistrain Nissle 1917—from bench to bedside and back: history of a special Escherichia coli strain with probiotic properties, FEMS Microbiology Letters, 363(19), fnw212. doi:1093/femsle/fnw212
  3. Schütz E. (1989). The treatment of intestinal diseases with Mutaflor. A multicenter retrospective study. Fortschr Med, 107(28), 599-602. PMID: 2693288
  4. Kruis, W., Fric, P., Pokrotnieks, J., Lukás, M., Fixa, B., Kascák, M., … Schulze, J. (2004). Maintaining remission of ulcerative colitis with the probiotic Escherichia coli Nissle 1917 is as effective as with standard mesalazine.Gut53(11), 1617–1623. doi:1136/gut.2003.037747
  5. Henker, J., Laass, M., Blokhin, B. M., Bolbot, Y. K., Maydannik, V. G., Elze, M., … Schulze, J. (2007). The probiotic Escherichia coli strain Nissle 1917 (EcN) stops acute diarrhoea in infants and toddlers.European journal of pediatrics166(4), 311–318. doi:1007/s00431-007-0419-x