Scientists have developed a new testing method that detects all known harmful E. coli strains.
Scientists at the U.S. Department of Agriculture’s Agriculture Research Service developed the test to detect bacteria that produce the shiga toxin, which causes diarrhea and disease.
Xiaohua He, a molecular biologist with the ARS in Albany, California, said the new test uses the same basic procedures as existing tests and could fit in with procedures now used at many slaughter plants.
“Yes, it can be used alone or as a confirmation test after traditional PCR (polymerase chain reaction) tests,” she said.
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“It helps eliminate false positive and false negative results often derived from PCR methods.”
She said the sample enrichment step, which is the same for the new test and the existing PCR test, takes about eight hours, and then the test itself takes about two more hours.
E. coli responsible for human illnesses are better known in the laboratory as shiga-toxin producing E. coli (STEC).
These bacteria are responsible for about 265,000 cases of illness each year in the United States.
In Canada, 470 cases of illness due to E. coli O157:H7, the most well-known of the shiga-toxin producing bacteria, were reported in 2013. Many strains of E. coli cause disease, but until now tests detected only some of them.
“We developed a set of novel monoclonal antibodies (mAbs) that can bind to all (shiga toxin) subtypes (of the E. coli bacteria),” he said. “Our assay uses a cocktail of these mAbs. Therefore, it can detect all STEC strains.”
She said the antibodies developed by her team also have potential to treat humans with STEC infections.
“Our study showed neutralizing mAbs could clear lethal doses of shiga toxin 2 from intoxicated mouse blood within minutes and protect mice from such doses for at least four weeks. We are currently working on a project to humanize these mouse derived mAbs for potential therapeutic uses.”
Patent licences have already been granted to commercial suppliers. A test kit for 96 samples costs about $700.
Terry Fries is a freelance writer based in Summerland, B.C.
