The bacterium E. coli is the most common cause of urinary tract infections and bloodstream infections. But in the search for a vaccine, researchers discovered that the bacterium is more resilient than they thought.
Most people have E. coli as part of their gut microbiome. As long as it remains in the intestine, it usually does not cause problems. However, if it spreads to other parts of the body, it can cause infections such as urinary tract infections and bloodstream infections. This can be especially serious for older people and cancer patients.
Increasingly resistant to antibiotics
Many people are given antibiotics to treat infections. However, due to frequent use of antibiotics, many variants of E. coli have acquired multidrug resistance. This means that some antibiotics no longer work against them, posing a major threat to public health.
Vaccines could reduce antibiotic resistance
Researchers therefore hope that it will be possible to develop a vaccine against this bacterium.
“It could reduce the use of antibiotics and be of great benefit to people with weakened immune systems, such as the elderly and cancer patients,” explains Rebecca Gladstone. She is a researcher at the Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo.
One vaccine is not effective against all infectious diseases
In the new study, published in Nature Microbiology, she and her collaborators collected data from 18,000 patient samples in many countries around the world. They studied the details of the bacteria’s genetic material through so-called genome sequencing.
E. coli, like most bacteria, has a protective capsule around it that helps it survive tough. Such capsules are made of different types of sugar layers behind which bacteria hide to evade our immune system and resist other environmental pressures.
And here the researchers faced a new challenge in their research. They discovered that there were more variations to this protection system than they had expected.
We discovered 90 different variants of such a protective capsule in E. coli. Only a third of these were previously known. ”
Rebecca Gladstone, Department of Biostatistics, Institute of Basic Medical Sciences, University of Oslo
Researchers plan to target vaccines against the most common variants that cause infections
However, there are a small number of variants that account for half of urinary tract infections and bloodstream infections in countries such as Norway. They cause many infections in which bacteria are resistant, meaning they are resistant to at least one type of antibiotic.
“The two most common capsules, K1 and K5, mimic human sugar-coated proteins that are present on the surface of our cells. Therefore, they cannot be used directly in vaccines. So for bacteria with these two types of capsules, we need to find other characteristics of the bacteria that vaccines can target,” says Gladstone.
“Norway can still achieve a lot by developing vaccines for just a few types of protective capsules. In low-income countries, the situation is more complex,” says Gladstone.
“There, there is even greater variation in these protective capsules. In any case, this means that we cannot develop just one vaccine that will work against all E. coli. We will probably need to focus on the types that cause infections most often and those that cause the most severe infections.”
Researchers must find new ways to kill bacteria
In the future, we may be at risk of running out of treatments for infections if bacteria become resistant to all the life-saving antibiotics we have.
“In addition to vaccines, we need to work on developing rapid diagnostics. It’s also important to find ways to kill bacteria without relying on large doses of broad-spectrum antibiotics,” Gladstone said.
The study was conducted in collaboration with researchers at the Wellcome Sanger Institute and was partially funded by the Trond Mohn Research Foundation.
sauce:
Faculty of Medicine, University of Oslo
Reference magazines:
Gladstone, RA; Others. (2026). Identification of transporter-dependent capsular loci associated with Escherichia coli invasion potential. natural microbiology. DOI: 10.1038/s41564-026-02283-w. https://www.nature.com/articles/s41564-026-02283-w
