Researchers find the mutation that makes E. coli so dangerous

Queensland researchers have discovered that a mutation allows some E. coli bacteria to cause severe disease in people. The mutation, which was found in the cellulose-making machinery of E. coli bacteria, effectively gives affected bacteria the green light to spread further into the body and infect more organs, such as the liver, spleen and brain. It has been described in the journal Nature Communications.

“Our discovery explains why some E. coli bacteria can cause life-threatening sepsis, neonatal meningitis and urinary tract infections (UTIs), while other E. coli bacteria can live in our bodies without causing harm,” said Professor Mark Schembri, from The University of Queensland’s Institute for Molecular Bioscience. “The ‘good’ bacteria make cellulose and ‘bad’ bacteria can’t.”

Bacteria produce many substances on their cell surfaces that can stimulate or dampen the immune system of the host. According to Schembri, “The mutations we identified stopped the E. coli making the cell-surface carbohydrate cellulose and this led to increased inflammation in the intestinal tract of the host.

“The result was a breakdown of the intestinal barrier, so the bacteria could spread through the body.”

In models that replicate human disease, the team showed that the inability to produce cellulose made the bacteria more virulent, so it caused more severe disease, including infection of the brain in meningitis and the bladder in UTIs. Associate Professor Sumaira Hasnain, from Mater Research, said the finding helps explain why certain types of E. coli become more dangerous and provides an explanation for the emergence of different types of highly virulent and invasive bacteria.

According to Schembri, E. coli is the most dominant pathogen associated with bacterial antibiotic resistance, having caused more than 800,000 of the almost 5 million deaths associated with antibiotic resistance in the year 2019 alone.

“As the threat of superbugs that are resistant to all available antibiotics increases worldwide, finding new ways to prevent this infection pathway is critical to reduce the number of human infections,” he said.

Image credit: iStock.com/Guntars Grebezs