August 07, 2008
Antibiotic-Resistant Bacteria Spreading

Jerome Groopman has a good article in The New Yorker surveying the growing threat of antibiotic-resistant bacteria.

Of the so-called superbugs—those bacteria that have developed immunity to a wide number of antibiotics—the methicillin-resistant Staphylococcus aureus, or MRSA, is the most well known. Dr. Robert Moellering, a professor at Harvard Medical School, a past president of the Infectious Diseases Society of America, and a leading expert on antibiotic resistance, pointed out that MRSA, like Klebsiella, originally occurred in I.C.U.s, especially among patients who had undergone major surgery. “Until about ten years ago,” Moellering told me, “virtually all cases of MRSA were either in hospitals or nursing homes. In the hospital setting, they cause wound infections after surgery, pneumonias, and bloodstream infections from indwelling catheters. But they can cause a variety of other infections, all the way to bacterial meningitis.” The first deaths from MRSA in community settings, reported at the end of the nineteen-nineties, were among children in North Dakota and Minnesota. “And then it started showing up in men who have sex with men,” Moellering said. “Soon, it began to be spread in prisons among the prisoners. Now we see it in a whole bunch of other populations.” An outbreak among the St. Louis Rams football team, passed on through shared equipment, particularly affected the team’s linemen; artificial turf, which causes skin abrasions that are prone to infection, exacerbated the problem. Other outbreaks were reported among insular religious groups in rural New York; Hurricane Katrina evacuees; and illegal tattoo recipients. “And now it’s basically everybody,” Moellering said. The deadly toxin produced by the strain of MRSA found in U.S. communities, Panton-Valentine leukocidin, is thought to destroy the membranes of white blood cells, damaging the body’s primary defense against the microbe. In 2006, the Centers for Disease Control and Prevention recorded some nineteen thousand deaths and a hundred and five thousand infections from MRSA.

But while MRSA is still a problem right now help is on the way with new drugs in the pipeline to treat staph infections. The more problematic threat comes from gram negative bacteria for which development of new antibiotics is more difficult.

Unlike resistant forms of Klebsiella and other gram-negative bacteria, however, MRSA can be treated. “There are about a dozen new antibiotics coming on the market in the next couple of years,” Moellering noted. “But there are no good drugs coming along for these gram-negatives.” Klebsiella and similarly classified bacteria, including Acinetobacter, Enterobacter, and Pseudomonas, have an extra cellular envelope that MRSA lacks, and that hampers the entry of large molecules like antibiotic drugs. “The Klebsiella that caused particular trouble in New York are spreading out,” Moellering told me. “They have very high mortality rates. They are sort of the doomsday-scenario bugs.”

The article points to the widespread use of antibiotics in livestock feed as contributing to the development of drug-resistant bacterial strains.

You might think this doesn't have anything to do with you. But you are one car accident away from being in a hospital. Also, the drug resistance mutations found in bacteria in hospitals will likely swap genetic material with other species of bacteria that are found more widely outside of hospitals. So more common bacteria might develop antibiotic resistance.

Share |      Randall Parker, 2008 August 07 11:01 PM  Dangers Pathogen Drug Resistance

Shannon Love said at August 8, 2008 12:57 PM:

I really wish we'd lose the whole "superbug" label because it leads people to believe that the microbes develop some new lethal property. They don't. The microbes merely become more difficult to treat putting us back to the days of our great-grandparents.

Anti-biotic resistant strains are not new. The first was identified in 1948 just a couple of years after the widespread introduction of penicillin.

The article points to the widespread use of antibiotics in livestock feed as contributing to the development of drug-resistant bacterial strains.

This is a trivial problem compared to people not taking full courses of antibiotics. In the developing world, it is common for people to take 10% of less of the optimum course. That comes to tens of millions of cases a year. Every time someone does this, they allow the most resistant microbes to thrive and spread. They're bodies become evolutionary laboratories selecting for traits that increase resistance.

No matter what we do, microbes will eventually evolve around all our antibiotics. Our only long term defense is to speed up the development of new antibiotics. Unfortunately, a new political culture which treats new drugs as a greater threat than the diseases they treat has slowed the development of new antibiotics to a crawl.

Brett Bellmore said at August 8, 2008 1:33 PM:

I'll believe the medical profession is concerned about things like this, when they rip the carpeting up in hospitals, and put tile in it's place, when visitors get masks, when UV sterilizers dot the walls. Hospitals are breeding grounds for multiply resistant strains because *doctors* don't care enough to do *their* part.

austex said at August 8, 2008 4:20 PM:

The media scare concerning MRSA is a little misleading. I have had patients with skin lesions that cultured out MRSA that were susceptible to Bactrim and Bactroban (old line, simple meds). I did end up referring one for recurrence to an Infectious Disease specialist who seemed more annoyed with yet another MRSA referral ("It's been around forever.") than concerned.

Patient non-compliance with antibiotic therapy is a big issue and is covered extensively in nursing and medical journals. I instructed one patient with MRSA to remove her acrylic nails, which are notorious for harboring any number and type of bacteria, and she returned for her follow-up appointment with all intact because she had had to go to a wedding and wanted to "look nice". Nothing more responsible than possibly spreading MRSA to an entire wedding party just because you want to look nice.

Randall Parker said at August 8, 2008 8:27 PM:

Shannon Love,

I doubt that partial courses of antibiotics are the biggest source of resistance development. First off, we have about twice as many prescriptions getting written than are justified. Second, we have the agricultural usage. These together probably account for about three quarters of all antibiotics usage.

Brett Bellmore,

If most medical doctors are not interested in the problem that doesn't make the warnings of those doctors who do care any less accurate.

Brett Bellmore said at August 9, 2008 4:23 AM:

That's true, but it remains a fact that, while the bad practices of non-doctors are creating strains resistant to new antibiotics, it's the bad practices of doctors that have turned hospitals into laboratories for combining those strains.

The medical profession knew how to do proper sterile procedure before antibiotics became available. They're going to have to stop being so reliant on antibiotics, and *combine* them with proper sterile procedures. So the antibiotics can be an additional line of defense, instead of having to bear the whole burden.

You can talk about how not completing a course of antibiotics helps the pathogen evolve resistance. But moving from somebody who's part way through such a course, to somebody who's on another antibiotic or none at all, does the same thing. Cross contamination between patients, and between patients and family, (Even other people's families!) is something we know how to prevent, have for a very long time. SHOULD be preventing. I mean, you can walk through a hospital full of people with compromised immune systems, coughing, and nobody stops you! Isn't that as much of an outrage as somebody stopping their antibiotics when they feel better?

As well as start using new procedures, such as deliberate inoculation with benign strains to fill the ecological niches they open up with the antibiotics. I think we're not doing nearly enough when it comes to actively recognizing that you're going to be populated by SOME strain of micro organism, so you'd best make sure it's a good one.

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