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Maryn McKenna answers questions about antibiotic resistance


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Maryn McKennaAward-winning science journalist Maryn McKenna participated in a live online chat about antibiotic resistance with Scientific American‘s Facebook page fans on April 11. Fingers flew fast as dozens of participants peppered McKenna with comments and questions about her story, "The Enemy Within: A New Pattern of Antibiotic Resistance," in our April issue, and related topics.

Below is an edited transcript of the 40-minute Q&A.

Scientific American: What inspired you to write this story?

McKenna: As some folks here may know, I wrote a book last year about the rising tide of antibiotic resistance worldwide, called SUPERBUG. SUPERBUG is about MRSA, or drug-resistant Staphylococcus aureus. Staph is a gram-positive organism. While I was working on it, physicians kept saying to me, "Well, MRSA is a problem, but what we’re really worried about is gram-negatives." And thus the story began.

Oddly enough, as I was working on it, the news broke of NDM-1, the extremely drug-resistant gene that is spreading from India. It creates drug resistance in gram-negatives, but it is only one facet of the problem. What made the whole problem [more] interesting is that much of the gram-negative tide has actually come from the U.S. CRKP [carbapenem-resistant Klebsiella pneumoniae—a K. pneumoniae infection that is resistant to the last-resort antibiotics called carbapenems] actually began on the East Coast and then moved to the rest of the U.S. and elsewhere in the world.

Nelson Pavlosky: It’s always seemed to me that the best response to dramatically resistant bacteria is for our society to dramatically cut back on the use of antibiotics, only using them in emergencies. Is there any serious effort to limit the use of antibiotics in everyday life and routine healthcare, anywhere in the world? If not, why not? Is this something we might see in the future?

McKenna: Yes, there are efforts to restrict antibiotic use; they’re generally called "antibiotic stewardship," and they are mostly operated by individual hospitals or medical centers. There is no requirement that hospitals do it, although most do in order to do good patient care. The Infectious Diseases Society of America proposed just last week that any institution that gets Medicare or Medicaid funding should be required to practice stewardship, precisely to try to slow resistance down.

Richard Mathews: I am wondering if our overuse of antibiotics in livestock is contributing to this problem.

McKenna: There’s no question that farm use of antibiotics plays a role in the rise of resistance overall. Whether resistance in gram-negatives is affected by that is less clear, because so far much of it is appearing in bugs that tend to affect people in hospitals, so the epidemiological links are less direct.

Question from Twitter: Could we recycle old antibiotics?

McKenna: Actually, we are, in a way. There are only two antibiotics that currently work against extremely resistant gram-negative bacteria, and one is a very old one that medicine held on the shelf for a while: colistin, or polymyxin E. It was on the shelf because it was considered toxic to the kidneys. So we are going back to older drugs for remedies. But could we stop using drugs, wait for resistance to die down, and then use them again? It depends on the mutation that confers resistance, and whether the bacterium needs to get rid of the mutation because it hobbles the bug in some way.

Brendan Maher: Is the French approach to testing and isolating patients with drug resistant strains effective? If so, why is it not used more widely?

McKenna: That’s a great question. They have only been screening for gram-negative resistance for a few months, so there isn’t a lot of data. But we do know, for instance, that when the Dutch started screening for MRSA at the doors of their hospitals, their MRSA rate stayed very, very low—much lower than it did in the U.S. But what France and the Netherlands have in common is that they are both single-payer health systems—and when you own the hospitals and employ the doctors, you have access to carrots and sticks that aren’t available to us here in retail-based U.S. medicine. There is one health system in the U.S. that is very like a European one in structure: the Veteran’s Administration. The VA started screening for MRSA in all its hospitals more than a year ago, and its infection rate and its costs went way down in response. So perhaps we should consider their example.

Andy Comanda: Do you think that maybe like in the movie "The Constant Gardener" that the drug companies may be responsible for this?

McKenna: Well, not deliberately! But the market behavior of pharmaceutical companies is part of this story, just as much as the behavior of medicine in overusing antibiotics. Here’s why: Many drug companies no longer find it profitable to make antibiotics, because there really isn’t much return in them. So they have been slower to bring out new antibiotics than, for instance, new lifestyle drugs. Therefore, when resistance takes a drug out, we don’t have a new one to use instead.

Moira MacNeill: Sales of bug-resistant hand soaps and other antibiotic cleansers make for resistance to those products, which then creates hospital infections. [Should we] ban the stuff?

McKenna: Great question. Those antimicrobial gels are pretty much never a good idea. Here’s why: We don’t really need them. Soap, or the alcohol in an uncomplicated hand gel, does the job of removing or killing bacteria without the need for extra antibacterial compounds. What those compounds do, actually, is to create a kind of resistance analogous to what antibiotics do. It is actually possible for bacteria to become resistance to antibacterial compounds, making them less effective.

Teresa Hartman: What information resources about antibiotic resistance should we medical librarians be connecting with our health professionals and consumers? Or are we too late for information to help stop the inevitable?

McKenna: Teresa, great question. It’s important that people be guided to information that they can use in their everyday lives. I think Medline Plus, run by the NIH at the National Library of Medicine (nlm.nih.gov), is really valuable and clear.

More resources:

http://www.cdc.gov/drugresistance/about.html

http://www.niaid.nih.gov/topics/antimicrobialresistance/understanding/pages/default.aspx

http://www.HealthCare.gov/compare

Image: McKenna





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  1. 1. byronraum 8:19 pm 04/11/2011

    I am not sure I understand why it should be less profitable to create an antibiotic rather than a lifestyle drug. I cannot talk to the issue that drug companies consider this to be so; but rather, trying understand the underlying reality. A lifestyle drug is forever. Tests on it have to go on for a very long time and you have to worry about accumulation over months and years. Such is not the same for antibiotics, which you take for a relatively short period of time. You can have a much shorter testing period and your potential liability is considerably less. It might take the same amount of effort to come up with the drug, subsequent verification should be considerably cheaper for antibiotics. Although you won’t make the same amount of money, your investment should also be less.

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  2. 2. 103md 10:32 am 04/13/2011

    byronraum, your comment suggests that antibiotics are cheaper to bring to market compared to lifestyle drugs. This isn’t necessarily the case. Average cost of bringing a drug to market, according to recent literature, is between $800 million to over $1 billion. Although I haven’t seen a good breakdown of this number based on the type of drug, the FDA approval process for antibiotics is quite rigorous and is a common topic of discussion among those who advocate for ways to bring more antibiotics quickly to market. Recent changes requiring the demonstration of "superiority" over "non-inferiority" for some antibiotic clinical trials have made it even more difficult and costly to bring a drug to market. I’m no expert… but the economics of drug development is a lot more complicated than considering the potential liability based on the length of a drug regimen.

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  3. 3. Elizabeth Combs 12:30 pm 04/27/2011

    An article that was written this month described a study done by the Arizona-based Translational Genomics Research Institute. The study found that there are high levels of resistant bacteria on meats in grocery stores . The Arizona-based Translational Genomics Research Institute examined one hundred and thirty-six meat samples from twenty-six different grocery stores in four states and in Washington, D.C. The study found that ninety-six percent of the meats that had staph bacteria present the bacteria were resistant to at least one antibiotic and that fifty- two percent were resistant to three or more antibiotics. The article explained the following: “… the most significant findings from the study aren’t the level of bacteria they found, but rather how the bacteria in the meat were becoming strongly resistant to antibiotics farmers use to treat the animals they slaughter.” (Ali 2011) This is a scary find! When the consumer brings home this contaminated meat, they are at risk for contracting infections that may be resistant to antibiotics. The article also explained, “The bacteria is always going to be there. But the reason why they’re resistant is directly related to antibiotic use in food animal production” (Ali 2011).
    It is still safe to buy and eat meat from a store, as long as you cook it and claen up after the raw meat.

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