Ask Dr. Hallberg: More about superbugs

More than two dozen cases involving highly drug-resistant bacteria have been reported in Minnesota in the last year and a half. These cases, along with superbugs from India, are raising questions about the use of antibiotics in humans and in the food stream.

MPR News medical analyst Dr. Jon Hallberg joined All Things Considered's Tom Crann to discuss the issue. Hallberg is a physician in family medicine at the University of Minnesota and medical director of the Mill City Clinic in Minneapolis.

Tom Crann: What is an antibiotic? How does it work?

Dr. Jon Hallberg: An antibiotic is a drug that ... works on bacteria only. And this is always important to remember that these do not help us against viruses or fungi or parasites, any of those kinds of classes of organisms. It's only bacteria.

They work because bacteria have a very unique structure. They have a cell wall, and our cells have a cell membrane. And we can take advantage of that and create a class of drugs that kills the bacteria.

Crann: Kills the bacteria - that's the way we think of them working. Is that always accurate?

Hallberg: Not really. There are two main ways in which these drugs work. They are classified as either being bactericidal, so actually killing the bug, the microbe, and they usually do that by almost puncturing a hole in the cell wall or damaging it in such a way it actually kills the bacteria.

But then there's a whole other class of bacteriostatic drugs, which sort of slow down the multiplying process, allowing our own immune system, which should be working anyway, to take care of them.

Crann: How do these germs or bugs or bacteria become resistant to antibiotics?

Hallberg: There's a couple different ways. First of all, when we're talking about killing bacteria, we're talking millions and millions of bacteria. These things are multiplying like crazy. So even if an antibiotic kills the vast majority of the offending microbe, there are still some left behind that are not killed. Our body can take care of those.

But some of them may also have a genetic mutation that circumvents the drug that we're using. In addition to that, there are other ways that bacteria can have injected into them through viruses, sort of these loops of genetic material that really get around the way that the antibiotics work. So they can happen by chance, or they can be sort of infected in a way by other bacteria or viruses.

Crann: This is actually counterintuitive, when we hear that the reason we have superbugs that are drug resistant is because of the use of antibiotics. Why is that?

Hallberg: Antibiotics are not smart drugs. I think we often think that. If I have an ear infection or I have pneumonia or a bladder infection, if I take this antibiotic, it's going to go right where I want it to. Well, it is, but it's also going to your scalp and your toes and it's going through your intestinal tract. It's going through your entire body, so it's killing a lot of different bacteria, but not all of them. And frankly, it's killing a lot of good bacteria.

So the more we use antibiotics and we don't need to, we're killing off healthy bacteria in many cases. We're kind of creating a survival of the fittest situation, where you've got these bacteria that are resistant to that drug that are left behind. They are now making copies and copies of themselves, and that's where the problem comes in.

Crann: How will these trends and the rise of superbugs affect the way, in the clinic, that you prescribe antibiotics?

Hallberg: There's been such a huge push over the last several years to not prescribe antibiotics unnecessarily. And people need to remember that. Just because you get a fever or your ear hurts or you have a sore throat, the vast, vast majority of the time, we do not need an antibiotic for that.

I think the message has finally gotten out in this country, in industrialized countries, that we shouldn't be using them if we don't need to.

The trouble is that in many, many places in the world, antibiotics are not regulated. You can get them over the counter at a pharmacy. You can get them in the black market, and people take them indiscriminately. So here, this is just yet another good reminder to us to not use them if we don't need to.

Crann: So whether it's the superbugs coming from India or the bugs we hear about in our midst, for health professionals, how worrisome is this?

Hallberg: I think it's worrisome. I know when I read the article, my heart sank for a moment. But then I think that in primary care, there are so many things I'm concerned about that this just sort of passes. But if I'm an epidemiologist, if I'm a hospital infection control person, if I'm an infectious disease specialist, I think this is the kind of thing that keeps me up at night a bit.]]

Crann: What are we going to do about them in the future?

Hallberg: The hope is that there are people working on new classes of antibiotics. There are so many ways in which bacteria make copies of themselves, that the antibiotics we have are great. They work in very specific ways, but there are many other ways that could be exploited that haven't been.

I think that there is certainly hope that a new class or new classes of antibiotics will be developed that will tackle some of these bugs.

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