Skip to main content /TRANSCRIPTS


Mayo Clinic Develops New DNA Test to Rapidly Identify Anthrax

Aired November 5, 2001 - 11:02   ET


BILL HEMMER, CNN ANCHOR: But before we do that, back to Minnesota. Let's listen in on what they are saying now at the Mayo Clinic.

DR. FRANKLIN COCKERILL, MICROBIOLOGIST, MAYO CLINIC: Mayo Clinic has developed a new DNA test to rapidly identify anthrax in human and environmental samples. We are pleased to be joined here today by our colleagues at Roche Diagnostics, who are making the test available to public health agencies, hospital laboratories, and reference laboratories in the United States and in other countries. I'd like to begin with some context. When a person is suspected to be exposed to anthrax, the first thing they want to know is whether the agent was, in fact, anthrax. Right now, local laboratories can quickly determine the presence of a bacterium. But they can't tell whether it is anthrax or not. The current process to identify the presence of anthrax is multi-step and may take several days. The events of the last several weeks require as rapid as a response as possible. Mayo Clinic scientists have developed a new DNA test that identifies anthrax in less than an hour, instead of days. Roche Diagnostics plans to provide the test to local and regional laboratories so that they will have the ability to perform rapid DNA testing, eliminating the waiting period currently requires at most laboratories to identify anthrax. The development is significant for the following reasons: First, it will bring rapid DNA testing to the local level with no need to wait for samples to be transported to a distant laboratory. Second, it will allow physicians to begin treating their patients who have been exposed in a more timely fashion. And third, it will more quickly alleviate undue anxiety for people who haven't been exposed. Because this test involves rapidly multiplying -- or what we say, "amplifying" anthrax DNA in our laboratory, the validation that we've been able to do to detect anthrax in samples that contain on a few bacteria is quite outstanding. A person who has been infected with anthrax typically will have millions or even billions of these bacteria in his or her blood stream very shortly after infection, particularly the inhalational form. In our laboratory we have been able to validate this test to detect only a few anthrax bacteria in a sample.

HEMMER: That's the gist of it, at the Mayo Clinic, what they are talking about now is a new test that can rapidly discover whether or not a person has been infected with anthrax and whether or not an environment has been tainted by anthrax as well. Elizabeth Cohen is with us. Jeanne Meserve is up in Washington. Let's talk about what day are talking about. First of all, it has never been tested, from my understanding, outside the laboratory. Is that correct?

ELIZABETH COHEN, CNN MEDICAL CORRESPONDENT: Exactly. And what they've done, what the Mayo Clinic did, and if this works, it could really be incredible news. What they did is they took healthy blood. They spiked it, as they said, with anthrax bacteria, and then saw if the test picked up. That's the first step you do. However, a Mayo representative told me today, they have not tried this out in real people. In other words, there are people out there in the community who are infected, as we know. They said they have not tried on any of those people to see if the test worked or not. And that's a big distinction to make. You go from the lab to real people. They have not, I've been told, made that real people step yet. Let's talk a little bit how this test works. It tests the actual DNA of the bacteria. So, what would happen if that if someone is infected with anthrax, if they breathe it in, eventually that anthrax bacteria would get into the blood, and they would be able to do a test to see if the DNA is there and then they would know if someone is infected or not. The reason why that's important is that right now, there is no good easy test to do for anthrax. So let's say a roomful of people -- someone opens up an envelope of anthrax. The CDC would just go in and give everyone in that room antibiotics. Because they just -- they just don't know. I mean, they can do some environmental testing. But they're really not sure at what point the -- how many people got infected, and as I said, there's no good way of testing. So, if there was a good way of testing, if there was good way to go in and say all right, you have anthrax infection, but you don't, so you get antibiotics and you don't, that would be terrific. And so, that's what the hope is for this test and other people are also working on rapid tests to see if they can decide who really has it and who doesn't.

HEMMER: This was news to me when I came in. Did we see this coming? Was this on the horizon?

COHEN: There are a couple of different people who have been working on these kinds of tests. I believe the CDC has been working on their own.

HEMMER: And the key thing that you mentioned in terms of human beings. You can get a result back if, indeed, this is successful, within a couple hours or possibly one hour time instead of waiting a couple days.

COHEN: That's true, but there's a distinction that I want to make. Let's say I right now were to inhale anthrax. How long take for those bacteria to get into my blood? I've asked this question of several doctors and they've all said, "we are not sure." So, let's say I were to inhale anthrax right now. The CDC came in an hour saying, "Elizabeth, let's test you." It may be negative because it just hasn't gotten to my blood yet. They may test me tomorrow. It could possibly still be negative because it hasn't gotten into my blood. That's a very important thing to remember with tests. They can only test for what's there. It takes time for this bacteria to get into the blood.

HEMMER: And the converse of that is the false positives we've heard about as well.

COHEN: Exactly.

HEMMER: Those who test positive at the beginning may prove to be negative.

COHEN: This testing is still in early stages.

HEMMER: Hang on one second. You're talking about the human effect, with regard to anthrax. Jeanne Meserve in Washington with us now, talking about the environmental effect. Make the distinction for us, Jeanne, if you could.

JEANNE MESERVE, CNN HOMELAND SECURITY CORRESPONDENT: Well, we're talking about the sample that you might find on a table or in an envelope that a first responder wants to test. This is still a laboratory-based test. You have to takes a sample to a laboratory. Have it test there. What first responders really want is something that they can take out into the field that is reliable. Right now, they do something that is a test for antibodies. It does give you false positives and false negatives, not 100 percent reliable. Lawrence Livermore Laboratories, the national lab, has miniaturized this same PCR technology that's being talked about today. That is being put into a small device that is going to be commercially manufactured and available in about 6 months' time to first responders. That's what the people in the field really want to see. On a slightly different note, I was talking to someone in the testing field, a competitor of Roche, talking about this technology announced today. They expressed to me the opinion that this is nothing earth shattering. They say this PCR technology has been out there for quite a long while. In fact, a variant of it was the very same thing used by weapons inspectors in Iraq years ago. So they're a little less than overwhelmed by this. I point out the fact that it's great if it's going be more widely deployed, but you're still going to need to have people who are trained to prepare the samples. Use the machines, and read the samples reliably.

HEMMER: Best case scenario, then, when we talk about all this. We talk about the buildings evacuated on Capitol Hill. It's likely, if this ever to prove good in the field and reliable and dependable, you would not necessarily have to shut down every building, correct?

MESERVE: Well, my guess is that probably you would do an initial evacuation because any of these test are going to take five, 10, 15 minutes to conduct. So, probably, in the interest of caution, there would be an evacuation. But, if you got negative result quickly, obviously, people could be brought in much more quickly to their place of work or wherever.

HEMMER: Interesting science. Jeanne, thanks. Quickly back to Elizabeth. When Jeanne was talking about that, you were shaking your head in agreement about it not necessarily be the newest of news because it has been used in other cases before, specifically testing in Iraq.

COHEN: Well, let me talk a little bit about PCR testing and DNA. And Jeanne was saying, this is nothing new. PCR testing has been out there. She's absolutely right. I mean, right now, you can do DNA testing for anthrax. However, very, very few labs do it. You can't just -- not just anybody can get it. It's hard to do, and its done by only a few very well-trained people. What Mayo is hoping to do is to make this an easier thing to do. They want to distribute this test to 25 labs and so that any -- so that it would be easier for anybody to do it. But again, it is unclear at what point in the person's disease process this would show a positive. If it only shows a positive when they're already really sick, how helpful is that? You already know that they're really sick. You don't need a test to tell you that.

HEMMER: And with time, I think science will get better, and we'll all have better answers.

COHEN: Yes. As always. As always.

HEMMER: Thank you. Appreciate it.




Back to the top