2008 August 07 Thursday
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.

By Randall Parker    2008 August 07 11:01 PM   Entry Permalink | Comments (5)
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