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New ‘superbug’ becomes first drug-proof bacteria to hit U.S.

May 26, 2016 at 6:30 PM EDT
A 49-year-old Pennsylvania woman has been found carrying a strain of E. coli that is resistant to last-resort antibiotics, which researchers say marks the first appearance of a drug-proof bacteria on U.S. soil. Scientists in Pennsylvania are working with the Centers for Disease Control to find a way to fight the superbug. Hari Sreenivasan talks to Dr. Beth Bell of the CDC for more.
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HARI SREENIVASAN: But first: a sobering new development with superbugs and public health concerns about the limited effect of antibiotics.

For the first time in the U.S., a person has been found to be carrying a strain of E. coli that’s resistant to antibiotics of last resort. The Washington Post reported the strain was discovered last month in a 49-year-old Pennsylvania woman. She was resistant to Colistin. And researchers said it — quote — “heralds the emergence of a truly pan-drug-resistant bacteria.”

Dr. Beth Bell is with the Centers for Disease Control and Prevention. And she is now working with Pennsylvania officials. She’s the director of the National Center for Emerging and Zoonotic Infectious Diseases.

Thanks for joining us.

First, how — what is so distinct about these findings?

DR. BETH BELL, Centers for Disease Control and Prevention: Colistin is an antibiotic that we have already had for quite a long time, but we use it as a last line.

So, it’s our drug of last resort. And so when patients are infected with some of these superbugs that we have talked about before, where the strain is resistant to pretty much every antibiotic, we rely on Colistin as the last resort.

And what we find here in this patient, the bacteria that infected this patient, is that her strain contains one of these mobile genes that confers resistance to Colistin. So, because bacteria can spread these mobile genes among themselves, it sets off a situation where we can see a bacteria that’s resistant to every known antibiotic. And, of course, that is a very frightening prospect for all of us.

HARI SREENIVASAN: Right.

So, when I am go to the pharmacy, and I’m prescribed something like azithromycin or something, it’s pretty low on the scale of the arsenal that doctors have. So, this is the top end. There is nothing after this. That means that the patient is untreatable, and that means there is a, what, greater chance that they might die because of this?

DR. BETH BELL: Sure.

There’s — we luckily haven’t seen actual bacteria that are resistant to every single antibiotic here in the United States. But there are reports of this in other parts of the world, and these patients have a very high mortality rate. It’s extremely difficult to treat them. And, again, this raises the specter of a post-antibiotic era.

HARI SREENIVASAN: All right, so how do bugs get this strong?

DR. BETH BELL: You know, bacteria are just really, really smart. Microbes have learned how to evolve over centuries and centuries, and they have a number of different methods for outwitting antibiotics.

And because, bacteria, they reproduce so quickly, by chance, sometimes there will be a mutation that allows a certain strain to outwit an antibiotic. And that, therefore, means that that bacteria grows preferentially, and that’s how these bacteria develop resistance.

And so, of course, that points out the importance of using antibiotics only at the right time and the right dose, because overuse of antibiotics, of course, can spur these bacteria to develop these resistance mechanisms.

HARI SREENIVASAN: But what can we learn from what happened to this specific individual? Right now, it’s just one person, but what do we know? Do we know anything about how she contracted this or perhaps if her immune system was already suppressed?

DR. BETH BELL: We don’t know much yet about how she contracted it. It doesn’t sound like she’s traveled outside the United States, but we don’t have the kind of really specific information that we would like.

We’re working directly with the Pennsylvania Department of Health right now to do that sort of in-depth investigation that will help us figure out why she might have gotten it, whether any of her household contacts also had the bacteria, and to just give us the kind of information that we need about how widespread the bacteria might be in this particular situation.

HARI SREENIVASAN: Over the past several months, the CDC has been out talking about so many different types of infectious diseases.

One on the hand, we have had Ebola, and now there’s lot of concern about Zika. This is something completely different. This isn’t the type of communicable disease that I can get by just being in the same room with you, right?

DR. BETH BELL: Yes.

Well, the mode of transmission of different — of communicable diseases varies by the bacteria. But certainly with some of these superbug strains, we do see them transmitted, especially in health care settings.

And that is why prevention really is so important, prevention in terms of antibiotic stewardship, using antibiotics correctly, and infection control, using the kinds of strategies that prevent environmental contamination in hospitals and spread of bacteria among patients.

HARI SREENIVASAN: All right, Dr. Beth Bell from the Centers for Disease Control and Prevention, thanks so much.

DR. BETH BELL: Thank you so much for having me.

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