Rapid 2-in-1 E. coli Test Unveiled

SAN FRANCISCOScientists have developed the first two-in-one test that can simultaneously detect both the E. coli in ground beef responsible for food poisoning, and the toxins the bacteria use to cause nausea, vomiting, diarrhea and other symptoms in its victims.

Our test may be used in meat processing plants to allow in-house testing of products prior to sale, said project leader John Mark Carter, PhD., of the USDAs Agricultural Research Service in Albany, Calif. This would reduce the frequency of foodborne illness, reduce product recalls and enhance public health while reducing annual cost for food testing.

Until now, separate tests were required for strain of bacteria. Current tests for E. coli in beef also are time-consuming and can take three to five days for results. The new test cuts the waiting time to just 24 hours, the researchers said. The test is slightly less sensitive than current tests, but scientists think the sensitivity can be improved.

The new test uses microscopic plastic beads, each 1/100th the width of a grain of sand, containing a fluorescent dye. The beads, customized in Carters lab, are coated with antibodies that lock onto proteins or antigens present on E. coli and its two main toxins. During the test, the beads are mixed together with ground beef or other food samples and then separated and run through an instrument. It identifies beads that have latched onto the E. coli antigens.

Finding a few E. coli bacteria in a large sample of ground beef or other food is like looking for a needle in a haystack, he said. This new method makes the needle much easier to find, compared to standard methods. But improvements in sampling and sensitivity are still needed.