MRSA: The Drug-Resistant 'Superbug' That Won't Die Superbug, a new book by journalist Maryn McKenna, tracks the spread of MRSA, the drug-resistant staph infection that seems to outwit every antibiotic thrown at it. McKenna explains how the bacteria has changed over the past 30 years — and how a vaccine may be the only way to stop it.

MRSA: The Drug-Resistant 'Superbug' That Won't Die

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This is FRESH AIR. I'm Terry Gross.

A lot of people that are admitted to hospitals worry not only about the problems that got them there, but also about hospital-acquired infections, infections from antibiotic-resistant bacteria that live in hospitals and can find their way into surgical incisions, IV sites or catheter sites. These bacteria are known as MRSA, M-R-S-A, an acronym for methicillin-resistant Staphylococcus aureus.

My guest, Maryn McKenna, has written a new book about the menace of MRSA, called "Superbug." In the book, she describes how a strain of this antibiotic-resistant bacteria is now living outside hospitals, in the community, and how it's spread into the food chain.

McKenna is a science and medical reporter who covered the Center for Disease Control for the Atlanta Journal-Constitution. She's now a contributing writer at the Center for Infectious Disease Research and Policy at the University of Minnesota.

Maryn McKenna, welcome to FRESH AIR. We've talked about MRSA on the show before, but your book was really, was really scary because I learned all these things I didn't even know about it. So let's start with the basics.

MRSA isn't just resistant to antibiotics. It's more lethal than many other bacteria. What kind of damage can it do?

Ms. MARYN McKENNA (Science and Medical Reporter, Atlanta Journal-Constitution; Author): The interesting thing about MRSA is that it does an extraordinary amount of things that it's taken a number of years for people to figure out.

So MRSA is an acronym, M-R-S-A, and the S-A stands for Staphylococcus aureus, which is a very large grouping of bacteria that have been with mankind for probably as long as we've been human, and you can tell that because there's a lot of tricks that it has for getting around our immune systems.

And it lives with us on our skin, in our nostrils, often without causing very much difficulty - until it can get inside our bodies through a scrape or a cut in the skin or an incision made for, say, a catheter. Then it can cause infestations of the valves of the heart. It can infect the inside of bones. It can cause very large abscesses, collections of pus that are walled off inside muscles.

More recently, it's been discovered that it doesn't actually need a cut or a break in the skin in order to cause disease, to cause illness. It can also start an infection on what looks like intact skin, and cause what medicine calls a skin and soft-tissue infection - which sounds like not a big deal, but can turn into a very large infection that requires surgery to get better.

GROSS: So tell me: Can the benign - seemingly benign staph that's residing in my nostril turn into this antibiotic-resistant infection if it enters a wound in my own body?

Ms. McKENNA: Yes. That was probably figured out first in the 1960s, when they started to be really good at microbiology, and they noticed that people who had staph infections, the infections were caused by the same strain that these people were carrying around in their nostrils.

So it's possible either that someone is carrying a staff strain with them and infects themselves or that, in a setting like a hospital, they pick up a strain from say, a health-care worker or someone else coming into the hospital and have an infection caused by that instead.

GROSS: Not to dwell on this too long, but does that mean like, don't pick your nose if you have a cut? Or like, what does it mean?

Ms. McKENNA: Right. It means, you know, for this bacterium that is causing a worldwide epidemic that we haven't really fully sussed out the size of yet, it turns out that some of the things we can do to defend ourselves - in fact, have to do to defend ourselves - are the sort of things that your grandmother would have told you to do: Don't pick your nose. Wash your hands a lot. That's pretty much it.

GROSS: Okay, so MRSA is famous for being a hospital-acquired infection. Why does this resistant bacteria dwell in hospitals?

Ms. McKENNA: People who are in hospitals are really good targets for infection. If you were a bacterium, you'd probably really like to live in them because their immune systems are damped down in a number of ways.

They might be elderly. They might be taking chemotherapy, either for HIV or for cancer. They might have had a lot of other antibiotics already that damp down the immune system. They might have a lot of cuts in their skin because of lines and IVs going in and out. So they present both a lot of portals through which bacteria can enter, and also reduced defenses in the body once the bacteria get in.

And in addition, there's really tight concentrations of lots of people who share those conditions, who are friendly places for bacteria to grow. And so there's a sort of it's just a very sweet target for bacteria. Once they're in there, they find it a very fruitful place to be.

GROSS: And why are hospitals so difficult to get rid of the resistant bacteria once they're in a hospital, whether it's on the floors or the bedrails, let alone being carried by your own health-care workers?

Ms. McKENNA: It's so challenging for so many reasons. You know, if it were easy, I think they would have fixed it already, though there are some things that are probably easy that aren't being done yet.

There are, as I've just said, lots of sick people. And there are also lots of really busy health-care workers who, because medicine is so complicated, so technological, and also now with managed care so very, very busy, have a lot of things to do. So there are steps that they may miss.

There's a lot of surveys now that say that health-care workers often miss simple opportunities to wash their hands, sometimes as many as 50 percent of opportunities - not because they're evil or because they intend to infect people, but because they're distracted and have very, very busy days.

And in addition, as you say, there are bacteria - and staph is one of them -that can live on surfaces in hospitals. So unless things were absolutely sterile all the time, it's unlikely that we would be able to make hospitals completely resistant-bacteria free.

GROSS: I've known about this antibiotic-resistant bacteria. I'm sure a lot of our listeners have known about it. One of the many things I didn't know before reading your book is that resistant bacteria has spread to the community.

So it's already been a menace in hospitals, but it's gotten out of hospitals, too. How is it being spread outside of hospitals?

Ms. McKENNA: MRSA lives not just in people who are debilitated and ill and in hospitals, but on all of us walking around all the time. But it was always thought - from about the 1960s, when it first sparked up, into the 1990s - that the only place where it was successful in attacking people was in hospitals, because they're debilitated and ill.

And then in the 1990s, a group of researchers at the University of Chicago noticed that they were seeing infections in children that looked very like those hospital infections, and yet these kids had never been anywhere near a hospital. I mean, they were at University of Chicago because they'd come to the emergency room with these infections, but they had not been in the hospital before.

And it turned out that there was a slightly different strain of staph that had adapted itself to live in the community and cause infections that are as serious, and sometimes more serious, than the ones that were being caused in hospitals.

GROSS: So how does it compare to the hospital version?

Ms. McKENNA: The first signal that something different was going on was that the kids that came to University of Chicago in the mid to late 1990s had infections that were caused by staph, and the staph was resistant, but the resistance pattern of the bacterium was slightly different. It was not resistant to quite as many drugs as the hospital variety.

And the second was that it was causing syndromes, illnesses that were slightly different than what was going on in the hospital. In the hospital, someone might have MRSA on the valves of the heart, a staph infection of the heart, endocarditis, because it had gotten into their bloodstream.

The ones - the kids at the University of Chicago were showing up with very large abscesses buried deep in their muscles. That was not anything that anyone had seen in the hospital patients before.

Later on, people started to see abscesses in bone, osteomyelitis, infection of the bone. Those were a slightly different category of illness, and they were also showing up in people who were a new category of patient.

GROSS: So in hospitals, when MRSA, this antibiotic-resistant bacteria, spreads, it's kind of understandable. People are lying there with open wounds and with catheters. How does the community version of this antibiotic-resistant bacteria spread?

Ms. McKENNA: It's still somewhat mysterious, because it's only been about 10 years that people have been studying this - and not very many people studying it. But it seems that there are a couple of factors, the kind of predisposed people.

The first is, it happens in situations where there's a lot of crowding. Think of a prison or an Army barracks. It happens in places where maybe hygiene isn't very good, so that there's a lot more bacteria staying on the skin. Again, think of a prison.

It happens when people have close skin-to-skin contact, and that probably explains why this tends to happen a lot in athletes, both pro athletes and kids who play school sports, because if a child crashes into another child in a football tackle, and one child has this on their skin and the other child gets scraped, then the bacteria can enter their skin there.

GROSS: Do parents have to worry about their children playing sports in school?

Ms. McKENNA: I think they should worry about their kids being clean when they play sports in school. And that sounds so simple and yet, you know what? I spent time in some schools when I was reporting this book, and there are things that kids do, such as not bringing their uniforms home to get washed very often, or letting their shoulder pads get dirty. And then there are things that schools do as well.

It was really astonishing to me to discover that kids no longer shower after gym class, because showering after gym class was one of the staple traumas of my adolescence, for sure. They don't do that anymore. And so if they've picked up a bacterium as they're out, you know, on the football field or field hockey or anything like that, it's going to be on their skin much longer.

GROSS: So another scary thing I learned from your book is that the drug-resistant bacteria that lurks in hospitals, and the slightly different variation of that Staphylococcus that is now being spread in communities, have merged. They've converged to form like, a third kind of resistant version of Staphylococcus. And why is this so dangerous?

Ms. McKENNA: So for about the past 10 years, since the community strain was first identified, you know, people thought they had this kind of sussed out. There was the hospital strain, and it affected people in hospitals. There was the slightly different community strain, and it affected people who were outside hospitals. When medicine says community - that's got quotes around it - it means kind of anywhere outside the walls of a hospital or a nursing home.

But what they started to notice was that people were hospital patients and yet were infected with the community strain, which meant that it behaved slightly differently, caused slightly different syndromes, and also was resistant to different drugs.

And then also you can see in some of the microbiology that's been done that people who are out in the community actually now have hospital strains. So what this means is just sort of that it's moving in an unpredictable manner, in a manner that's not very well-detected. The reason it's not very well-detected is because we still don't really have very good surveillance for MRSA, either hospital or community.

And the ultimate point of this is that this makes it much harder to say, when someone is detected as having a MRSA infection, exactly which drugs are going to work. So you have to use the most intense drugs immediately, until you can figure out which of the sort of less-important drugs might work for the hospital or the community strain. And the more that we use the most intense drugs, the faster the bug is going to develop resistance against those as well.

GROSS: It's very frightening to think that drug-resistant bacteria are living not only in hospitals and nursing homes, but they've gotten out to the community, and it can spread in schools and other institutions. But how worried about this should we be? I mean, is this like, reaching epidemic proportions? Or is it just that we've documented a few cases where this new strain of the antibiotic-resistant Staphylococcus has spread?

Ms. McKENNA: I think we should be worried, which is not the same thing as being panicked about it. But here's why we should be worried: first, because there does seem to be a really large amount of this out there. One of the best estimates that's been done so far, out of not very many estimates, is that about 1.5 percent of the population - which is more than 4 million people -walks around with this on their nostrils or in their skin that's MRSA, not just staph. And we still don't have a perfect understanding of when that carrying around - that bacterial carriage, as it's called - turns into an infection. So we can say that those people are at some degree of risk.

The second is that - the second reason to be concerned - is that since we know there's a large amount of it out there, and since we know that bacteria are really good at kind of exchanging and trading resistance factors, it means that there's a big pool of bacterial population out there that is potentially getting more resistant, or becoming resistant in unpredictable ways, that isn't well-measured and detected because we're not looking for it.

GROSS: What advice would you have for us to try to protect ourselves? Wash our hands? Anything else?

Ms. McKENNA: I'm smiling because it's such an overwhelming problem, and yet something as simple as washing our hands does seem to be personally protective.

I mean, there are policy things that we should be doing: counting it better, looking for it more. But on a personal level, washing your hands - and asking your kid to shower after football - is not a bad idea.

GROSS: Why is it that bacteria that are resistant to potent antibiotics are vanquished by soap?

Ms. McKENNA: So I have to preface this answer by saying that I'm not a chemist and I'm not a microbiologist, but here's my understanding of it. The way that antibiotics attack bacteria is in a particularly designed way. It's as though a key is fitting in a lock. And so when bacteria respond to that and evolve a protection against it or a workaround, it's as though they've shut off the lock.

Things like soap and water, and hand sanitizers - which contain alcohol or salt -don't attack in that fine-pointed way. They're really kind of more like whacking the bacteria over the head with a hammer. I mean, they simply break them open, kill them, and then the friction of either massaging your hands with soap and water, or massaging them with a hand sanitizer, actually physically washes them away.

GROSS: If you're just joining us, my guest is Maryn McKenna. She's the author of the new book "Superbug: The Fatal Menace of MRSA." And MRSA is the acronym for Methicillin-resistant Staphylococcus aureus. In other words, it's bacteria that are resistant to antibiotics, and it's become pretty dangerous. And she's a science and medical reporter. Let's take a short break here, and then we'll talk some more. This is FRESH AIR.

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GROSS: If you're just joining us, my guest is Maryn McKenna. She's a science and medical reporter, and her new book is called "Superbug: The Fatal Menace of MRSA." MRSA is Methicillin-resistant Staphylococcus aureus. In other words, this is the bacteria that is resistant to antibiotics.

I was alarmed to read that there have been a few instances where this antibiotic-resistant bacteria has spread from human to pet to human. How much is that happening? How much has that been documented?

Ms. McKENNA: How much it's been happening, and how much it's being documented, are unfortunately two separate questions. This was really kind of discovered by accident. What turns out to happen is that pets can pick up the human strain of MRSA from their humans when because they live with us closely, because we smooch them on the noses.

They can hang onto the strain - not very long term, necessarily, but just long enough that if say, the human has an infection, recognizes the infection, and goes to their doctor and gets antibiotics that do take care of it, by the time the antibiotics are done and the human is clear of the infection, the pet still is holding onto it - and passes it back to the human in that same kind of daily interaction that gave it to the pet in the first place.

There are families who have had a kind of ping-ponging infection in their household for months or years, and it's not until someone has the thought to check the pet - the cat or usually, the dog - that it turns out that that's the missing piece of the family puzzle.

Now staph aureus, the staph strain that infects humans, the S-A in M-R-S-A, is not naturally something that lives in animals. Animals have other staph strains that are unique to them. So it's not surprising that it took a while to figure this out, because no one was really looking for MRSA in household pets, and it's just a fairly recent discovery - and again, not yet a lot of research, not a lot of counting to see how much it happens.

GROSS: Any advice for people who have pets?

Ms. McKENNA: Well, veterinarians who have looked at this worry that people are going to overreact. And they say, you know, first, if it happens, it's not your pet's fault. And second, it probably doesn't happen all that often. But if you are one of those unfortunate people or families that seems to have a recurrent staph infection, where you get one of these severe skin and soft-tissue infections or even something more serious, and you get it treated, and it doesn't go away, and you do the kind of things that might chase it out of your household, like washing everything down with bleach, and it still doesn't go away, and you have a pet in the household, that would be a good time to check your pet.

GROSS: One doctor who you follow in the book described MRSA as the perfect pathogen. What makes it perfect, in a diabolical way?

Ms. McKENNA: The astonishing thing about this bug - once I started reporting on it, I really understood why people spend their entire lives in research on it -is that it's very difficult to not act as though it has a personality, because it seems so smart.

Now, it's not, in fact, smart. It's the blind persistence of natural selection, but natural selection seems to be working really well for staph.

So first, it has all this ability to live with us in a manner that is pretty much unchallengeable. We can't eradicate staph. It's part of our personal flora and part of our environment. Then it has this really sophisticated array of defenses and workarounds for our immune system. It's got abilities to turn on resistance factors. It's got a wide variety of genes that are specific to that. It also produces toxins that destroy muscle and burst cells.

And in addition to all that virulence and all this ability to live in our environment and on our bodies, it is very smart in developing resistance as well. It - I understand why that particular researcher called it the perfect pathogen. And when he said that, it was with a rueful kind of admiration.

GROSS: What are some of the drugs that stand the chance, now, of being effective against antibiotic resistant bacteria?

Ms. MCKENNA: MRSA turns out to be a really interesting case because on the one hand, it has become resistant to a wide variety of antibiotics that we use every day. And what all of those antibiotics have in common is a sort of central feature in their chemical structure called the beta-lactam ring. We talk about it as though it's methicillin, but methicillin gave that structure to several families of antibiotics; there are now dozens of them.

And so particularly with the more serious cases, there are only a few antibiotics that are already on the market that are left. The one that everyone talks about is one called vancomycin, but there are some other, newer ones: daptomycin and linezolid. The interesting thing is that there are also some older drugs, drugs that have been around for a very long time that are off patent - so they're relatively inexpensive - that may work against this as well.

The problem is that since they're older drugs, people tend not to do that much research on them because theyve been around for a while; they dont make anyone a lot of money when they're sold; and they're just not high on the list of anything that anyone wants to look at. And for the very simple infections, it may turn out that the best thing to do may be not to give people drugs at all. If you just have a simple abscess, it may be that what you do is just kind of incise that, and let it drain and heal.

So the odd thing about this very challenging bug is that sometimes, it takes the very newest things that pharmacology can produce, the very most difficult and expensive drugs. But sometimes, it may take only some very simple drugs that we haven't looked at yet, but we need to start looking at - and sometimes maybe no drugs at all.

GROSS: Antibiotics are such commonly prescribed drugs. I was astonished to read in your book that pharmaceutical companies are not making antibiotics a priority. In fact, theyve become a pretty low priority. They're not seen as a financial winner in the industry. Why not?

Ms. MCKENNA: That actually really amazed me, too. But if you think of a pharmaceutical company as, you know, a business concern that is responsible to shareholders, unfortunately it makes a lot of sense. Imagine that you are a pharmaceutical company, and you want to come up with an antibiotic against something like MRSA. So maybe its a new antibiotic. So you think the older drugs dont work. This one is going to have a very significant market.

So the estimate that you hear a lot is that it takes about $800 million and at least five years, maybe 10, to bring a new drug to market. You spend all that money. You invest all that time. And at the end, you have a product for which the bacteria are going to develop resistance within a year or two years or five years.

In some areas, if a hospital sees resistance in maybe 15 or 20 percent of the particular class of bacteria they're giving that antibiotic for, theyll stop prescribing it because they can't guarantee that it's going to work. So now you have a drug for which you invested tons of time, and tons of money, that only has a marketplace life of a couple of years. And in addition, maybe people take it twice a day for 10 days. If they have a very bad infection, maybe they take it for a couple of months.

If I were that pharmaceutical company, it would make a lot of sense to me to instead make insulin, which people take every day for the rest of their lives, or Cialis or Viagra, which people probably take every day for the rest of their lives as well. There's a - much more return on a safer investment there than it is for an antibiotic.

GROSS: So does that mean our antibiotic research has really fallen behind?

Ms. MCKENNA: It means that companies have turned away from antibiotic research. There's a point in the book where I run down the names of companies that used to make antibiotics, that dont make antibiotics anymore. Now, if you talk to people in the pharmaceutical industry, they will say that the market structure for antibiotics needs to change, and they need more incentives from the government in order to do the research that's necessary.

I find it difficult to take the position that pharmaceutical companies need more help. And yet, it seems pretty clear that the marketplace is voting, that fewer companies are making antibiotics than used to. And if we want more antibiotics, or better antibiotics, there has to be something in there that needs to change.

GROSS: What about the possibility of a vaccine that would inoculate us against resistant strains of bacteria?

Ms. MCKENNA: If you talk to people who spend their lives researching staph, they will all bring up the possibility of a vaccine. I, myself, am skeptical of this - not so much that I think it can't be done, although there have been several attempts that have not done very well so far. They look promising in their early steps and yet, they dont make it all the way through all the trials that are necessary.

But what I think is dismaying about this is that we have become a culture that is not, at the moment, very interested in taking vaccines. This recent flu pandemic is a very good example. People are skeptical of vaccines in a way that they did not use to be. So if we said, well, here's a new vaccine, which was very expensive to produce and we'd like people to take it so they will protect themselves against MRSA, I do not think we can guarantee that the uptake for it would be very good. It's possible that if a vaccine were achieved, that you could define certain groups of people who ought to take it.

Maybe you give it to people just as they're going into surgery to be sure that they aren't going to have a surgical infection. Maybe you give it to women just as they're going to give birth so that they dont pick up a community infection in the birthing suites - which seems to be happening more and more. But the likelihood that a brand-new vaccine is going to be broadly accepted by the population seems a kind of low probability to me.

GROSS: One of the problems that we're facing with this antibiotic-resistant bacteria is that it's gotten into the food chain. And the way it's gotten in there is through the tons and tons of antibiotics that is fed to livestock animals. So where is MRSA in the food chain now? Can we pick up this drug-resistant bacteria by eating certain foods? Is it by touching animals? Is it just getting out in the air?

Ms. MCKENNA: There's a couple of layers of risk here. The first is that this new strain of staph that seems to be resident in livestock has been found in varieties of food animals throughout the European Union and in Canada and in the United States. In addition, its been found in people, people who have direct contact with animals - with farm animals who are getting antibiotics. It's pretty clear they are picking it up. We dont yet know how much - how often they pick it up.

The second is that there's a separate set of study - again, just a few people are doing it - that has found this bug, this animal-adapted strain of staph, on retail meat in several countries. If you took the meat home and had it in your kitchen and cooked it and ate it, you probably would not be made ill by swallowing it.

The kind of staph that we're talking about is not the kind that survives in your stomach and gives you food poisoning. But what is very likely is that you could handle it - handle that meat - and get the strain of staph that it is harboring on your skin. So now you have a resistant bacterium, a differently resistant form of staph, that's joining that population on your skin and could cause an infection at some unpredictable, future time.

The third layer of risk is that here, we have another enormous population of livestock worldwide that could be harboring a resistant strain of bacteria that is not being very well-tracked, and could be serving as a kind of pool in which resistance could spread or merge or change in a way that's not being keep track of.

GROSS: Now, how has the use of antibiotics in livestock contributed to the development of this drug-resistant strain that is now in livestock?

Ms. MCKENNA: There's a couple of different ways that antibiotics get used in food animals. The first is a process that's still somewhat mysterious, but goes back more than 50 years, that's called growth promotion. A couple of researchers discovered a number of decades ago that if you gave very low levels of antibiotics - much smaller than a treatment dose - to animals, they would grow faster. They'd put on weight faster.

And when the point of raising animals in a farm is to get them up to market weight as fast as possible, that seems like a good thing. So that's smaller than treatment doses of antibiotics. The second is that if you think of the size of a farm, if you have disease in your flock or herd, or the threat of disease, youre not going to single out a single pig or a single cow. It's much more efficient to give treatment doses of antibiotics both to the sick animals and to their near neighbors.

When we do that in humans, give antibiotics to people who are not sick, we call it inappropriate use of antibiotics. And a parallel thing is happening in farming, where especially on these very large, industrial farms, where animals are confined very closely and are at more risk of disease, they get antibiotics. They then become essentially breeding grounds for unpredictable varieties of resistance.

GROSS: So all of the measures that we're taking to prevent the spread or the development of drug-resistant bacteria in humans, we're not taking those precautions with livestock. And that's becoming a real problem.

Ms. MCKENNA: So the best estimate at the moment for what proportion of antibiotics are used in humans versus in animals at any time, is that only about 30 percent go into humans. And 70 percent go into livestock and food animals. And the 30 percent that go into humans are tracked much more closely than the ones that go into animals are.

GROSS: What do you think we should be doing now as a society, to stop the further spread of drug-resistant bacteria?

Ms. MCKENNA: It's a really challenging question because this is a problem that has a lot of strands in it. The first is, of course, that there are individual protective steps we can take. You know, there are things like washing our hands and asking our kids to shower after sports. But there are things that are kind of designed into the way we live our lives right now that make it very difficult.

For instance, there are large numbers of antibiotic prescriptions written for humans every year that really aren't necessary. People go to the doctor. They have what feels like a cold or bronchitis or an infection, and they ask for antibiotics. Or even worse, it happens more frequently, they ask for antibiotics for their kid and the doctor tries to say, well, this may not be a bacterial infection. We'd like you to wait a couple of days.

But we haven't come up with anything else as a society that kind of signals a successful encounter with a doctor other than an antibiotic prescription. If the doctor says to us, I'd really like you to watch for a couple of days and see if this is a virus or a bacteria, we feel kind of unsatisfied, as though we haven't gotten what we go for.

In addition, if it's a child youre talking about, we all live very busy lives. If you have a child and you need to get that child into day care, that day care is probably not going to want to hear that you want to keep your child in day care with an active infection - for three days - until you figure out exactly what that infection is.

They are probably going to want to know that your child is on some kind of drugs. So there's a way that we have structured medicine so that it all leads toward the desire to prescribe and to receive antibiotics, and nothing else feels quite as satisfying. Weve also, with the advent of managed care - not that that's brand-new anymore - we have so squeezed the days of doctors and other health-care professionals that it's actually quicker for them to give us a prescription than it is to spend another 10 or 15 minutes explaining to us why we dont really need that prescription after all.

And when people try to do this on a hospital level, when they try to say in a hospital, we really dont think you should be using those drugs; we dont think you should use this category of drug, or we think you should hold back from using these drugs, it gets into further levels of complication beyond just the individual encounter between a patient and a doctor.

It gets into issues of what the hospital funds, what it's willing to pay for, how much the physicians - who may not actually be employees of the hospital but may be subcontractors - how much their autonomy feels threatened because they're being told they can't use particular drugs. Its very, very complex.

GROSS: You know, because there's so much drug-resistant bacteria in hospitals, although a lot of hospitals are working really hard to prevent the spread of that, a lot of people are afraid to go into the hospital when they need something done. They're afraid that they'll acquire an infection.

What precautions can patients take when they're going into a hospital or a nursing home?

Ms. MCKENNA: So the first thing I want to say in response to that is that while I dont want to frighten anyone away from going to a hospital or a nursing home, I do think that that concern is legitimate. The people I talked to in the course of reporting this book who had hospital infections had just grievous infections. Their lives were changed by them. So its not a paranoid concern to worry about this.

So what do you do? It seems pretty clear that the most common point of infection is in the encounters between patients and health-care workers. What that requires is that patients, or their family members, really have to be defensive in their own behalf. And it's an easy thing to say but a hard thing to actually do, to be in the vulnerable position of being a patient in a hospital and say to the health-care workers walking in and out of your room, please dont touch me until I see you wash your hands, and yet that is in fact what may be necessary.

GROSS: Because of the H1N1, people are going crazy with Purell and with disinfectant sprays, spraying doorknobs and, you know, there's Purell - wherever I go there's like, Purell dispensers now or some, you know, some equivalent of that. What would you recommend in terms of a hand cleanser? What ingredient should we be looking for so that we protect ourselves without creating more resistant bacteria?

Ms. MCKENNA: There's things you want to look for, and things you want to avoid. The things that you want to look for are things that have just alcohol or salts in them. What you want to avoid are things that have other antibacterial agents in them as well, because that's just another version of overusing antibiotics.

If we overuse antibacterial agents, then that could breed resistance in our environments as well. And that's actually kind of hard to do, to avoid those, because they are now antibacterial chemicals in so many everyday products, in -not only in hand sanitizers but in cutting boards, in kid's toys, in things that you would have every day in your kitchen, sort of appliances and so forth. It's an expression, I think, of our being paranoid about germs - of being germaphobic - that there's a market for those.

GROSS: What is the greatest myth about how germs are spread that you would like to tell us about?

Ms. MCKENNA: You know, I acknowledge that in writing about scary diseases and in particular, the scary bacteria MRSA, that's its entirely possible that I'm making people paranoid. One of the first readers of the book, when he returned the draft to me, said, this makes me want to take a thousand showers. And while on the one hand I was pleased because that was kind of what I was going for and I really had had an impact, on the other hand, I dont want to make people so germaphobic that they do not - that they cannot live their lives.

So I think the things to be aware of are the things that we can control. You can control washing your hands a lot. You can control, if you live in a city where there's a subway and lots of people are holding on to the subway rail, you can control having a bottle or something uncomplicated like Purell in your purse or in your pocket. You can control when you go to the doctor or take your kid to the doctor, whether youre using drugs in an appropriate way.

To go around our lives feeling as though there's this cloud of threat around us all the time puts us in the position where we tend to over-respond. And when we over-respond, we use too many antibacterial products, we use antibiotics inappropriately. And then without realizing it, we make worse the situation that weve already gotten ourselves into with this international epidemic of drug-resistant bacteria.

GROSS: Maryn McKenna, thank you very much for talking with us.

Ms. MCKENNA: Oh, thank you for having me.

GROSS: Maryn McKenna is the author of the new book "Superbug: The Fatal Menace of MRSA." You can read an excerpt from "Superbug," and find expert advice on preventing staph infections, on Web site,

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