Certain gut bacteria are more common in countries like Norway than in a number of other countries and the incidence of bladder cancer, bowel cancer and prostate cancer is also higher. These findings could pave the way for new opportunities to prevent these types of cancer, according to a new study.

Previous studies have shown that a toxin produced by certain bacteria to dominate the interior of the intestine damages healthy cells and increases the risk of developing bowel cancer.

In a new study, scientists looked at the incidence of bladder, colon, rectum and prostate cancer and compared it to the prevalence of two toxin-producing E.coli bacteria in the affected countries. E.coli is the most common cause of urinary tract infections and bacterial bloodstream infections worldwide.

Norway has a higher incidence of bladder cancer and colorectal cancer than many other countries.

– During the study, we also found that the prevalence of these two E.coli bacteria was higher in Norway. When we compared equivalent data from several different countries, we discovered a clear trend: the fewer E.coli bacteria circulating in the population, the lower the incidence of these types of cancer, and vice versa , explains Jukka Corander, professor at the Department of Biostatistics at the Institute of Basic Medical Sciences, UiO, and leader of the study recently published in Lancet Microbe.

Can destroy DNA in cells

In recent years, intense research has been carried out internationally into the link between the toxin produced by these bacteria, called colibactin, and several types of cancer. The research was launched after groundbreaking studies revealed that colibactin damages the DNA of intestinal cells and scientists produced models of intestinal organs and found that toxin-producing E.coli caused cancer in the models.

In this new study, the team used a new analysis method, developed by researcher Tommi Mäklin, in collaboration with Corander.

Scientists have discovered that a certain subtype of E.coli developed a stable relationship with these harmful colibactin-producing genes centuries ago. The E.coli bacteria then began to use this toxin to eliminate its competitors and gain a dominant position in the human intestine. But this development has not occurred uniformly in all regions of the world.

– We have data representing the genetic material of 50,000 E.coli samples collected on four continents. When we studied them, we found that the ability to produce the toxin is very limited and is mainly found in two particular genotypes of E.coli bacteria. These two viruses circulate frequently in Norway and are also the main genotypes causing infections in the blood in our country. In contrast, these bacteria genotypes are rarely found in countries like Pakistan and Bangladesh, Corander explains.

The scientists involved in this study therefore put forward a number of hypotheses according to which ecological conditions would keep these undesirable bacterial families away from certain population groups.

Scientists want to examine the possibilities of developing vaccines or favorable microorganisms

Corander believes that if scientists were able to develop vaccines against the harmful type of E.coli that produces colibactin, or a form of probiotics, it would result in notable public health benefits. Probiotics are live microorganisms which, taken at the right dose, can benefit the health of the host via an alteration of the intestine. microbiota. The idea is that these measures could eliminate unwanted colibactin-producing bacteria from the intestines.

– If we can develop a vaccine that helps the body fight these two types of E.coli, we hope to be able to significantly reduce the incidence of infections and reduce the use of antibiotics. Most importantly, we can potentially reduce the risk of bladder, colon and rectal cancers and perhaps also some prostate cancers, he says.

The study was carried out in collaboration with scientists from the Wellcome Sanger Institute and the University of Helsinki.