I Dream of Genes Without Resistant Scare
by Bill Chameides | March 8th, 2010
posted by Erica Rowell (Editor)
There’s new evidence of a steady rise in antibiotic-resistant bacteria in soils.
Throughout much of human history, almost any bacterial infection could end up taking a life. Either we recovered from the infection by a kind of Russian roulette with our immune system or a folk remedy, or we didn’t. And many didn’t. Many a death resulted from a cut that today we would think nothing of. What happened?
Antibiotics Discovered in Early 20th Century, Antibiotic Resistance Discovered Soon After
The development and use of antibiotics have profoundly changed our lives. Most likely a significant number of us would not be alive if antibiotics were not in force. But that tide may be turning.
Normal evolutionary pressures help bacterial strains become resistant to antibiotics, and as that happens, they become more dangerous. Penicillin, the so-called miracle drug, is far less effective today than it was in 1945 when its developers won the Nobel Prize in Medicine.
As a result, we find ourselves in a deadly Darwinian race: we must develop new antibiotics to fight bacteria faster than they evolve to beat the antibiotics. This race has a perverse Catch-22. The more we use a given antibiotic to fight infection, the faster bacteria will develop resistance to the antibiotic, rendering that antibiotic ineffective.
As Nicholas Kristof described in Sunday’s New York Times, we may be falling behind in this contest because of the overuse of antibiotics.
One increasingly familiar antibiotic-resistant bacteria (aka superbug in the parlance of the popular press) is Methicillin-resistant Staphylococcus aureus. Commonly referred to as MRSA (pronounced mersa), the bacteria cause staph infections that are difficult to treat. According to the Centers for Disease Control, staph infections from MRSA have increased from two percent of all staph infections in 1974 to 63 percent in 2004. (Further reading here [pdf].)
Resistance to Antibiotics Being Spurred by Prophylactic Use in Animal Factory Farms
Losing the race because we were trying to cure people with antibiotics wouldn’t be so bad — after all, that’s what the antibiotics are for. But most of the antibiotics being used in the United States are for prophylactically enabling the mass production of chickens, and hogs, and cattle in concentrated animal feeding operations (CAFOs).
Here’s a mind-boggling statistic: According to the Union of Concerned Scientists, 70 percent of the antibiotics used in the United States are given to healthy livestock.
That’s healthy livestock. We’re not using most antibiotics to cure sick livestock, let alone people. We’re using them to prevent diseases so that we can crowd cattle and pigs and other animals into tight quarters and get them to grow faster and larger. (Examples here and here.)
Paper: Significant Rise in Antibiotic Resistance to All Antibiotics
Now a paper by Charles W. Knapp, currently of the University of Strathclyde, Scotland, and colleagues documents the rise of antibiotic resistance in the environment.
The authors, whose findings were published last week in the journal Environmental Science and Technology, used genomics to identify antibiotic-resistant genes in soil samples gathered in the Netherlands between 1940 and 2008.
They found evidence of a significant rise in resistance to all major antibiotic classes over the time period. The rise in resistance to tetracyclines, a class of drugs used with regularity when I was a kid for everything for acne to cholera, was especially striking: increases of up to a factor of 15 since 1970.
At the end of the paper, Knapp et al. wonder whether their findings suggest that:
- there may be an “increasing chance of encountering organisms in nature that are resistant to antimicrobial therapy”;
- there’s a possibility of transmission of antimicrobial genes in soils from one pathogen to another, creating entirely new strains of antibiotic-resistant bacteria; and
- the soils may provide a reservoir of antimicrobial genes long after “more prudent antibacterial use is common.”
Here’s what I wonder: Has the drive to put a steak, pork chop, or chicken on every barbeque grill let the antibiotic-resistant genes out of the bottle?filed under: animals, bacteria, faculty, food, health
and: antibiotic resistance, antibiotics, concentrated animal feeding operation (CAFO), evolution, farms, New York Times, Nicholas Kristof