PNAS paper shows that the bacteria could be separated into groups called clades, which relate to severity.

A team of researchers report developing a quicker technique to separate E. coli strains based on specific SNPs. Using this, they were able to isolate more virulent ones.  

“It used to take three months to score one gene individually,” says Thomas Whittam, Ph.D., Hannah distinguished professor at the National Food Safety and Toxicology Center at Michigan State University (MSU). “Now, we are working with a new, more rapid system that can do thousands of genes per day.”

Using this system, which detects SNPs in 96 loci of the bacteria, the researchers looked at the DNA of more than 500 strains of O157:H7. They discovered that individual bacteria could be separated into nine major groups called clades.

E. coli makes people sick because they produce toxins, called Shiga toxins. These toxins block protein synthesis. What the investigators found was that the different clades produced different kinds of Shiga toxins in varying amounts based on their DNA.

“For the first time, we know why some outbreaks cause serious infections and diseases and others don’t,” Dr. Whittam reports. 

Aside from MSU, researchers from the University of Medicine and Dentistry of New Jersey, Michigan Department of Community Health, Illinois Institute of Technology, and the Centers for Disease Control and Prevention were also invovled. The study was published on March 10 in the Proceedings of the National Academy of Sciences.

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