New Anthrax Test Gives Results in 35 Minutes
Nov. 5, 2001 -- Forget about nose swabs. A new test for anthrax exposure gives results in under an hour. Current tests take days and don't always detect the deadly bacteria.
"The first thing people want to know in a case of suspected exposure is whether the agent was in fact anthrax," says Franklin R. Cockerill III, MD. "The events of the last several weeks require as rapid a response as possible.
Cockerill, a microbiologist at Mayo Clinic, Rochester, Minn., led the team that developed the test. They used technology from Roche that quickly magnifies DNA from a sample and matches it to anthrax DNA. Now that researchers have the anthrax DNA template, any laboratory equipped with the Roche instruments can test samples. The machines now are in use at more than 400 labs in the U.S. and at more than 1,500 labs worldwide. The U.S. CDC and its affiliated labs also have devices capable of performing these tests, known as polymerase chain reaction or PCR assays.
The DNA test detects anthrax in samples from the environment -- or from a person's blood. It's not meant as an every-day way to be sure you're safe. And it can't say for sure that a person has anthrax disease. But for people who suspect they may have been exposed to anthrax, the rapid test results will make a big difference. Those truly exposed can begin early, effective treatment. Those who turn out not to have been exposed can avoid the expense and side effects of unneeded drugs.
"This rapid identification will enable doctors to begin more timely treatment of patients who have been exposed to anthrax, and it will more quickly alleviate undue anxiety for people who haven't been exposed," Cockerill says.
The test is extremely sensitive. Soon after anthrax infection, people usually will have millions or billions of anthrax bacteria in their blood. The new test can detect as few as five bacteria in a blood sample. To make sure it doesn't say there are anthrax germs when none are there, the test uses four different probes for anthrax bacterial DNA. Still, these tests use only fresh blood to which anthrax has been added. There have been no real-life clinical tests.
"This is because there has not been a real-life, large-scale outbreak of anthrax, thank God," Cockerill says. "But we are confident we can identify anthrax in under an hour. The actual time, once a sample is received, is about 30 minutes."
At first, Roche will give the test to labs for free. The Swiss company currently is negotiating with the U.S. FDA for accelerated approval of the test. After approval, the company will charge for the test.
The test initially will be given to 24 private laboratories across the U.S. that are not now part of the CDC's laboratory network.
"This test is not intended to compete with the CDC but to complement CDC efforts," Dennis Coverdale, vice president of corporate communications for Roche Diagnostics Corp., tells WebMD. "This test is to verify exposure. It is very sensitive. It is accurate, but it doesn't replace the CDC's tests needed for final confirmation of anthrax infection. But it certainly gives people an earlier indication of exposure than they've got now."