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Opinions vary on rapid anthrax testing

By ELLEN BECK, UPI Science Reporter   |   Nov. 5, 2001 at 4:14 PM   |   Comments

WASHINGTON, Nov. 5 (UPI) -- Mayo Clinic and Roche Diagnostics on Monday outlined a new, rapid DNA test for anthrax that cuts the time for test results to less than an hour but the Centers for Disease Control and Prevention said growing the bacteria in a culture remains the gold standard diagnostic.

Mayo microbiologist Dr. Franklin Cockerill III said the new test to detect anthrax bacteria in people as well as in the environment can detect as few as two bacteria and gives results in "less than an hour instead of days." People often have millions of anthrax bacteria in their system shortly after infection by the pathogen.

"It will allow physicians to begin treating their patients who have been exposed in a more timely fashion," Cockerill said. He added laboratories can now quickly determine if a bacteria is present, but "they can't tell whether it is anthrax or not."

The Mayo test, which has not been validated in actual field testing, is to be made available to local and regional laboratories this month -- free of charge at first.

The test was developed using Roche's LightCycler instrument for polymerase chain reaction or PCR based assays. Only the CDC and a few other large laboratories around the country have this type of testing ability.

Mayo issued a statement that said it had been working with the federal government to make the test formula available to federal agencies that request it. It said Roche was working with the Food and Drug Administration "to determine requirements for expedited regulatory approval."

Dr. Bradley Perkins, an anthrax expert with the CDC in Atlanta, said to his knowledge, the agency had "not been in contact with Mayo clinical researchers in the evaluation of or (had) interaction regarding these tests."

Perkins said while there is room for new anthrax diagnostics, CDC would want the Mayo test to be compared to and validated against its own polymerase chain reaction or PCR assays it uses in the field before making any determination on efficacy. PCR testing is a selective way to detect the genomic sequences of bacteria. Its ability to detect very low levels of genetic material is well documented in medical and scientific literature.

Perkins said, however, the gold standard for confirming anthrax remains actual growth of the bacteria in a laboratory culture, which can take up to several days.

He said CDC also was not using nor advocating the use of rapid field testing techniques for detecting anthrax in the environment, adding validation of such tests has been incomplete and tends to show an inappropriate sensitivity rating. He said rapid field testing often can require 10,000 anthrax spores to be present before a positive reading is given, which would be fine for a letter loaded with anthrax powder, but inappropriate for testing an entire building, which often comes up with a spore or two in an isolated area.

As the CDC continued to investigate existing anthrax cases, in Washington the government on Monday opened some buildings shut down for anthrax testing even while additional anthrax spores were being discovered.

The Supreme Court returned to its usual home to hear argument Monday, the first time the justices have met on Capitol Hill in more than a week. Chief Justice William Rehnquist made no mention of the recent anthrax scare as he called the day's argument to order.

An air filter at the court's off-site mail-screening facility in Maryland tested positive for the anthrax bacterium late last month. A little more than a week ago, anthrax also was found in the main mailroom of the court itself.

However, 440 court employees and journalists tested negative for anthrax exposure, and no anthrax was found in the rest of the courthouse.

In an indication that normalcy is returning to the Hill -- much of the nearby congressional office space also reopened Monday.

At the Pentagon, however, six post office employees and one Navy service member are on antibiotics after a test of two post office boxes showed signs of anthrax Saturday.

The post office in question is a U.S. Postal Service facility. The separate Pentagon mail distribution center room has been tested twice since Oct. 15 with negative results. Seventeen private post office boxes were tested Oct. 30 for anthrax; two of them were positive.

One belongs to the Navy sailor who has gone to the Bethesda Naval Hospital where he is being tested and is believed to be on a course of antibiotics. Six civilian post office employees are taking the antibiotic Cipro, according to a Pentagon official.

The CDC Monday said it has confirmed 17 cases of anthrax infection and continues to watch five suspected cases. Four people have died from inhalation infection -- two in Washington, one in Florida and one in New York.

Florida has two confirmed inhalation cases, New York has one confirmed inhalation, along with four confirmed cutaneous or skin anthrax infections, and three suspected cutaneous cases. In New Jersey, confirmed cases include three cutaneous and two inhalation, as well as two suspected cutaneous infections. In Washington, there are five confirmed inhalation cases.

The most recent inhalation death, that of Kathy T. Nguyen, 61, a stockroom employee at the Manhattan Eye, Ear and Throat Hospital in New York, continues to baffle investigators although there is one new clue to the case.

New York officials said the woman's death is a homicide but cannot connect her to any of the other anthrax links, such as the postal service, Congress or the media. Perkins said Monday they are following the lead she may have worked in a New York restaurant, but had no other information on what that may mean or where it might lead.

Perkins said while investigators have a good timeline for her illness after she was hospitalized "beyond that we are having difficulty identifying all aspects of where she might have been, how she might have been exposed in the two weeks prior to illness."

Environmental testing has turned up no anthrax in Nguyen's personal belongings, at her apartment or any other places she was known to have been. He said comparing her case to the other inhalation deaths shows she is out of the potential exposure time range to have come in contact with any of the known anthrax letters sent to Senate Majority Leader Tom Daschle, NBC or the New York Post.

He said, however, CDC does not believe she was infected through cross contamination of mail and added the agency also does not believe cross contamination would present enough spores to cause anyone to get inhalation anthrax.

Perkins said the agency had no plans to vaccinate people simultaneously for anthrax and smallpox, but added CDC staff were attending smallpox readiness training and had been vaccinated against the virus, which is not susceptible to antibiotic treatment.

(With additional reporting by Pam Hess and Mike Kirkland in Washington.)

© 2001 United Press International, Inc. All Rights Reserved. Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI's prior written consent.
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