The rise of antibiotic-resistant bacteria has got many experts predicting a future in which currently tractable diseases, like tuberculosis, became untreatable again. The popularity of modern antibiotics, ironically, is what is leading to their downfall: antibiotics in consumer products, like soaps, as well as the excessive use of antibiotics by people who have no bacterial infections, help select for strains of bacteria that don’t respond to drugs. Factory-farmed livestock, which receive tremendous doses of antibiotics in their feed, are also a likely breeding ground for resistant bacteria that could potentially infect humans.
Proponents of factory farming have scoffed at such claims [pdf], but now, scientists have provided definitive evidence that this happens: through genetic analysis, they found that a strain of MRSA, already resistant to one family of drugs, had hopped from people to farmed pigs, acquired resistance to another antibiotic being fed to the pigs, and then leapt back into humans, taking its new resistance with it. That strain, called MRSA ST398 or CC398, is now causing 1 out of 4 cases of MRSA in some regions of the Netherlands [pdf], where it arose, and it has also been found across the Atlantic in nearly half of the meat in US commerce. After this strain arose in 2004, the European Union began a ban the use of antibiotics in livestock feed. In the United States, however, where most of the antibiotics in circulation are being used in farming, no such regulation exists.
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