A study suggests that a harmless strain of Escherichia coli called Nissle 1917 primes the small intestine to defend itself against another strain that causes potentially fatal infections.
Most strains of the bacterium E. coli are benign, but some can cause severe illness, including stomach cramps, vomiting, and diarrhea. The bacteria can spread via contaminated food and water or through contact with an animal or person who has the infection.
Other strains can cause urinary tract infections, respiratory illness, and pneumonia.
Some of the most dangerous E. coli strains produce a toxin called Shiga. In the United States, the Centers for Disease Control and Prevention (CDC) estimate that these strains are responsible for 265,000 infections annually.
They note that a strain called E. coli O157 causes about 36% of these infections. E. coli O157 can infect people of all ages, but infections can be particularly severe, and even fatal, in younger children.
Antibiotics are unsuitable for treating these infections because they can provoke the bacteria to produce more Shiga toxin, which can trigger a potentially fatal kidney condition called hemolytic uremic syndrome.
“Right now, there is no cure for an E. coli infection,” says Alison Weiss, Ph.D., a professor at the University of Cincinnati College of Medicine, OH. “We can give individuals fluids, but [the infection] can be really deadly, and it would be really nice for us to figure out how to cure it.”
Weiss and her colleague Suman Pradhan, Ph.D., wondered whether a probiotic could prevent infections, based on observations dating back to the early 20th century.
For more than 100 years, doctors have used a “friendly” E. coli strain called Nissle to prevent and treat infectious diarrhea.
Alfred Nissle, a German physician and researcher, first isolated the strain from the feces of a soldier during the First World War.
In 1917, Dr. Nissle noticed that in contrast to his fellow soldiers, the man did not develop diarrhea during an outbreak of the highly contagious bacterial infection shigellosis.
More than a century later, the strain of E. coli that was named after Nissle is the active compo