Bowel diseases: fight bacteria with bacteria

Bowel diseases: fight bacteria with bacteria

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Gut flora: Nissle bacteria protect against EHEC

Escherichia coli bacteria are generally perceived as pathogens. Certain strains that make up the so-called Shiga toxin can cause dangerous diarrheal diseases (EHEC). A research team has now shown that the non-pathogenic E. coli bacterium can protect Nissle from the pathogens.

Researchers from the American Society for Microbiology found that the bacterium Nissle, which belongs to the Escherichia coli, protects against dangerous intestinal pathogens. Nissle bacteria are harmless to the intestinal mucosa and at the same time prevent the harmful effects of pathogenic germs.

What are EHEC bacteria?

Enterohaemorrhagic Escherichia coli (EHEC) is a bacterium that produces Shiga toxin, a harmful protein. EHEC can cause severe diarrhea. With severe courses there is bloody diarrhea with cramping abdominal pain. Extensive kidney damage is also possible. An EHEC disease can be life-threatening for children, the elderly, or people with poor immune systems.

Nissle - a proven probiotic

Nissle bacteria have been used as a probiotic for intestinal health for more than a century. The bacterium also has an effect in the treatment of inflammatory bowel diseases such as ulcerative colitis. The research team at the University of Cincinnati wanted to understand whether Nissle can also protect the intestinal tissue from EHEC and similar pathogens.

Gut organoids open up new insights into the gut flora

The researchers examined various types of bacteria in intestinal organoids, i.e. human intestinal tissue that was grown from stem cells for experimental purposes in the laboratory. In this way, new insights into the behavior of the bacteria could be gained. To this end, the researchers colonized various organoids with EHEC or Nissle bacteria.

EHEC breaks through the natural protective layer of the intestine

The outermost cell layer of the intestine is called the intestinal epithelium. This layer also acts as a protective mechanism. The researchers showed on the organoids that EHEC bacteria are able to break through this epithelium.

Battle of the E. coli tribes

In contrast, Nissle bacteria were completely harmless to the intestinal epithelium. If EHEC bacteria were colonized on an organoid that was already inhabited by Nissle bacteria, there was a real fight between the bacteria. The population of Nissle bacteria declined rapidly, but there was no damage to the intestinal epithelium. The team observed the same thing when uropathogenic E. coli strains responsible for urinary tract infections encountered Nissle bacteria.

"Basically, the Nissle bacterium was killed by the pathogenic bacteria, but it made the intestines more resistant to damage," explains research director Dr. Alison Weiss.

Nissle as an EHEC therapeutic?

The study results indicate that Nissle can inhibit pathogenic intestinal germs and that it may be suitable for the prevention of such diseases. On the other hand, the results also indicate that Nissle populations are killed by Shiga toxin-producing bacteria, which could limit their usefulness as a therapeutic. In future studies, the researchers want to investigate the complex interactions between the types of bacteria in real human intestinal conditions. (vb)

Author and source information

This text corresponds to the specifications of the medical literature, medical guidelines and current studies and has been checked by medical doctors.

Graduate editor (FH) Volker Blasek


  • American Society for Microbiology: Fighting E. coli with E. coli (published 07.07.2020),

Video: Bacterial Infections in Humans (February 2023).