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PRI's Environmental News Magazine

Antibiotic Resistance

Air Date: Week of September 1, 1995

Faced with a barrage of medicinal attack, bacteria are fighting back. The strongest are adapting and surviving the onslaught of antibiotics which most doctors eagerly dispense, and their patients demand. Should the medical community curb widespread use of antibiotics? Do patients compromise their immune systems by going for a fast fix? Bob Carty of the Canadian Broadcasting Corporation reports.

Transcript

CURWOOD: This is Living on Earth. I'm Steve Curwood. Something is going terribly wrong with our antibiotics. These drugs have saved millions of lives in the 20th century, but they are suddenly not curing certain diseases any more. In fact, in the US, 70% of all infections that people get while in the hospital are now resistant to antibiotics. The reason, many scientists say, is simple ecology. Bacteria and the other microorganisms live in balance with each other and humans. Antibiotics upset that natural balance by killing off the most susceptible germs. But those which survive are the strongest and most deadly. And these germs can multiply with astonishing speed, since they figured out how to beat antibiotics, and they no longer have to compete with their more benign cousins. Bob Carty has our report.

THEROUX: My name is Camille Theroux, and I was a truck driver. I went in on the 22nd November '92 for an aneurism operation.

DOCTOR: Complications ensued, which required application of many antibiotics aimed at preventing him from getting more ill.

THEROUX: 13 different types of antibiotics.

DOCTOR: The result of all this was in due course that he developed totally antibiotic-resistant organisms.

THEROUX: Where this came from I have no idea, this bacteria eating me out, you know. And I still don't know what it is.

(Hospital monitors beep; hospital workers talk)

CARTY: His friends call him Tiny, and he's a living bookmark in medical history. While in an Edmonton hospital, Tiny developed an infection his doctors had never seen before. Something no antibiotic could kill. Tiny is alive because his doctors resorted to a treatment out of the last century: cutting away his infected flesh.

(More beepers, more hospital personnel)

CARTY: Antibiotics are failing us and people are dying. The US Centers for Disease Control estimates 13,000 Americans die annually because of infections that antibiotics can no longer cure. It's a brave new world, and it frightens Tiny's doctor, Mark Huele.

HUELE: Organisms are arising that are very resistant and they aren't all new and unheard of organisms. A lot of them are old standbys that we thought we had nailed down very effectively. It's a very scary proposition.

CARTY: It's scary because it's challenging the way we think about medicine and the natural world. We used to think that bacteria were a problem and antibiotic drugs were the solution. Now, that equation doesn't work. Because our drugs have changed the natural world, and that change may mean the end of an era in modern medicine. An era that began not so long ago.

(Recording: "Here at St. Mary's Hospital Medical School in Paddington, through this very window, a speck of mold blew in and settled onto Professor Fleming's culture plate." Jazz music plays...)

CARTY: In 1928 Alexander Fleming found some curious green mold growing on a petri dish, and it was killing the bacteria around it. Before Fleming stumbled upon what he called penicillin, bacteria were the world's deadliest scourge. They killed half of all surgery patients, a third of pneumonia cases, almost everyone who got meningitis. In war, more people died of infections than from gun wounds. What a difference a drug makes.

(Recording: dramatic background music: "Disease, whose guerrilla warfare against the Red Cross flag has hitherto out-generalled even the greatest commanders, suffers a setback, thanks to the new miracle drug penicillin...")

LEVY: Penicillin was, of course, the first miracle drug. Why? Because it was so wonderful at killing bacteria and not harming the person. And patients who had terminal illnesses with a bacterial infection were somehow revived.

CARTY: Dr. Stuart Levy is a Professor of Microbiology at Tufts University School of Medicine in Boston. Levy is also one of the leading scholars on antibiotic resistance and the author of The Antibiotic Paradox. He points out that within years of its appearance, some bacteria developed a resistance to penicillin. But no matter. Drug companies just developed new antibiotics.

(Jazz music plays.)

LEVY: Tetracyclines, and chloroenphenicols, and cyclosporins, and the other aminoglycocides like gentomycin. they all came relatively soon in the '50s and '60s. And then discovery was slower. We still had some coming out in the '70s, derivatives of the ones that were found first. Then the 1980s were a little less, and then we get to the '90s with none.

CARTY: Today there are no new antibiotics about to come on the market. Meanwhile, bacteria have made an amazing comeback. For every antibiotic in use, there is at least one resistant bacteria. Some bugs can defeat almost all of them. That leaves us exposed to dozens of diseases, some of them very common, and increasingly dangerous.

LEVY: Start right from the top. Ear infections in kids, which then may be in meningitis, which is severe. The organism which causes strep throat. You get pneumonias which are resistant. Urinary tract infection: how many women have found that they start with one antibiotic, didn't work, I've got to start another one, then I've got to start another one. You have infections following surgery, you have abscesses, blood-borne infection...

CARTY: But how did this happen? How do bacteria become resistant to antibiotics? In a word: evolution. Like all organisms, bacteria evolve in response to changes in their environment, and antibiotics introduce a huge change in a bacteria's environment: a new selective pressure, as evolutionary biologists call it. At first, antibiotics kill all bacteria. But occasionally, some bacteria have little mutations that give them a survival advantage. They defy antibiotics. And since the susceptible ones are killed, the resistant ones can simply multiply freely. Stuart Levy says it's not such an unfamiliar process.

LEVY: It makes me think about the old days, perhaps, when herbicides and pesticides being used on plants were not so specific and if you overused them, you essentially cleared out the lawn. And the only thing left is a single plant of something like crabgrass, or another weed, which is resistant. Well, in that area now, that plant can multiply without any competitors, and what you're left with is a lawn of weeds resistant to the very therapy you used. And I think that that's what happens in a microcosm, in a small way, when you take an antibiotic.

CARTY: And don't underestimate the lowly germ. Since the discovery of penicillin, we humans have evolved a mere 2 generations. But in that same period, bacteria, which reproduce every 20 minutes, have gone through the equivalent of 18 million years of human evolution. They've learned a lot. Like how to pick up resistance from other species of bacteria, even from viruses. So even without the presence of antibiotics, normal bacteria can pick up resistance defenses from resistant bacteria. Dr. Michel Bergeron is the head of infectious disease research at the Laval University Hospital in Quebec City. He likes to use a metaphor to explain bacterial defense systems.

(Dramatic film soundtrack music plays)

BERGERON: Just imagine an army attacking a city. But a walled city. The antibiotic is the army here. The army goes in.

(More dramatic music; thousands of movie extras cry out)

BERGERON: The bacteria will have walls; that's the first line of defense of the bacteria. Some bacteria don't let the army in. The wall of the city becomes much thicker because they've been exposed to these antibiotics.

(Different war music: exploding bombs)

BERGERON: Now, if you're successful, and you breach the wall with your antibiotic or with your army, you go into the city. Now the second line of defense are soldiers within the city.

(Hollywood war continues: a man shouts, "... attack. We need more men out here!"...)

BERGERON: These are enzymes. The bacteria have soldiers that we call enzymes, and they're just things that destroy the army or the other soldiers or the antibiotic.

("Hold your fire...hold your fire. Take out!" Bomb explosions.)

BERGERON: So you see there's many lines of defense.

CARTY: And we are the ones who've made this all possible. By trying to kill bacteria with antibiotics, we have instead given them new life. Dr. Stuart Levy has seen patients die as a result. One was a man he was treating for leukemia and for what seemed like just a minor infection.

LEVY: We had every confidence that we were going to take care of the infection and take care of his leukemia. It was instead the infection that we weren't able to treat. And the infection got ahead too fast. Then I found out that he routinely treated himself, he had a relationship with his physician whereby he could gain access to any antibiotic he wanted. So in a sense, as he told me, he would have a medicine chest loaded with different antibiotics, and sometimes he would call his physician and sometimes he wouldn't. He'd just take them.

CARTY: Antibiotic misuse gives bacteria a perfect environment for developing resistance. And there are many kinds of antibiotic misuse. There's the doctor who over-prescribes antibiotics. There's the patient who demands antibiotics for things like a common cold, which is caused by a virus, not a bacteria. There's the working parent who doesn't complete a full course of antibiotics for a child and who keeps the remnants in the medicine chest to use at the next sign of a cold. Big mistakes. Such usages kill off sensitive bacteria that could keep infections out and allow resistant ones to develop and to come in. And then there's the problem of antibiotics in the food system. Almost half of all antibiotics are used in agriculture to help fatten our cattle and chickens and pigs. People can acquire resistant bacteria at the dinner table. And resistant bacteria are increasingly common, in our bodies and in our environment.

LEVY: In fact antibiotics have put a stress on the environment and on ecology, because the bacteria that we now see out there in the waters, in certain areas, hospitals, sewage systems, they're all resistant. Whereas before, they were consisting mostly of susceptible bacteria.

CARTY: Dr. Levy believes we have altered bacteria more in the past 50 years than in their previous 4 billion years of existence. And it's too early to know what those alterations mean for all the ecosystems where bacteria live.

LEVY: It's hard to make a comparison with other forms of ecologic change, such as burning of the rainforest, but I must say, counting the numbers of types of living organisms affected, then antibiotics are doing a similar effect.

(Clacking sounds in a laboratory)

CARTY: In his laboratory in Quebec City, Dr. Michel Bergeron is trying to find a partial solution for antibiotic resistance. There would be less resistance, he explains, if doctors could use the right antibiotic on the right bug. However, it currently takes 48 hours to get bacterial test results. So when doctors first see a patient, they often prescribe a broad spectrum antibiotic to kill as many possible kinds of bacteria.

BERGERON: Well by doing that, broad spectrum antibiotic favors resistance. Because you expose the microbe, who is very smart, to your best drug. So what does the microbe? He adapts himself. And becomes resistant. My solution is that we have to develop what I call rapid diagnostic tests that will allow the doctor to have the result of the microbe that cause the infection within an hour or so.

CARTY: Dr. Bergeron is developing kits for rapid diagnosis of bacteria. Patents are pending; talks are underway with drug companies. But this is all several years away. Meanwhile, the best medicine may be less medicine. European studies suggest that when antibiotics are limited, bacteria lose their resistance and become susceptible once again. Our antibiotics need not become obsolete, though they will never again be miracle drugs. What doctors fear most is what they call the event. There are bacteria now that are resistant to all antibiotics, but fortunately these bacteria are not very lethal. The fear is that one day, and it's a matter of when, not if, that total resistance will be picked up by a deadly bacteria. The Centers for Disease Control says that event could challenge the entire medical system. Dr. Michel Bergeron agrees.

BERGERON: I think we really were controlling our universe and controlling the bacteria very well up to now. I call it an apocalypse because at this stage we're not ahead. The bacteria is ahead. The bug is ahead of man right now.

(Hospital beeper)

CARTY: For Living on Earth, I'm Bob Carty.

 

 

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