ARS researchers examine test plates for STEC. Agricultural Research Service.
ARS molecular biologist Xiaohua He (right) and technician Stephanie Patfield observe results of a new test that can detect Shiga toxins from E. coli bacteria.

Test uses novel antibodies to detect STECs

USDA scientists develop a highly sensitive test that is able to detect all known Shiga toxin-producing E. coli strains.

U.S. Department of Agriculture scientists have developed a highly sensitive test that, for the first time, is able to detect all known strains of Shiga toxin-producing Escherichia coli (STEC).

According to the Centers for Disease Control & Prevention, STEC bacteria are responsible for more than 265,000 cases of illness and 3,600 hospitalizations each year in the U.S.

Developed by scientists at the Agricultural Research Service’s (ARS) Western Regional Research Center in Albany, Cal., the new test relies on ARS-patented antibodies, USDA said.

Most people have heard of E. coli O157:H7, which is often the cause of publicized foodborne illness outbreaks. However, many other kinds of E. coli can cause disease.

Several commercial tests are used to detect these bacteria, but none are capable of recognizing all STEC. Antibodies used in current tests recognize only a subset of Shiga toxins, not all Shiga toxins, USDA explained.

Tests using the newly developed antibodies are very sensitive. They can identify all known subtypes of STEC and rapidly detect new and emerging serotypes, according to ARS molecular biologist Xiaohua He. They also can be used to screen foods for contamination early on.

Additional studies have shown that these antibodies also can detect Shiga toxins in blood -- an indication that they can potentially be adapted as therapeutics for human diseases caused by Shiga toxins, according to ARS research leader Luisa Cheng.

USDA said the new antibodies have been licensed to Abraxis LLC, TechLab Inc. and List Biological Laboratories Inc.

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