I was pleased to see the recent editorial ("Troublesome antibiotics," April 3) addressing the widespread practice of feeding antibiotics to livestock. These antibiotics, many of which are the same drugs that are used to treat critically ill patients, are added to feed to promote growth and as a prophylactic measure to limit the spread of infectious disease among animals housed in crowded unsanitary conditions.
The editorial correctly points out that this troublesome practice promotes the spread of antibiotic resistance among bacteria, a major public health concern that is only getting worse.
It is important to realize that antibiotics in animal feed do not eliminate bacteria from animals; far from it. Instead, the composition of the community of bacteria living in and on the animals is changed. Those that were never susceptible to the drug or those mutant strains that have become resistant are selected. When bacteria are constantly exposed to antibiotics, they adapt to become resistant through changes in their DNA or in how that DNA is expressed.
Because bacteria are remarkably good at exchanging DNA with each other, resistance genes can spread rapidly from one species to another, especially under constant selective pressure from antibiotic usage. The National Academy of Sciences estimates that drug-resistant bacteria add $30 billion annually to our health-care costs, not to mention the tragic personal costs of losing loved ones to infections that used to be treatable.
The Provo/Orem community recently lost a young physician due to a staphylococcal infection. Recent research shows that some of the most difficult to treat staphylococci and their resistance genes are circulating freely among animals and humans.
The editorial alludes to a rule that the Food and Drug Administration passed 35 years ago that would have limited such non-therapeutic use of antibiotics in agriculture, which the FDA has not been willing to enforce because of pushback from some members of Congress, farm lobbyists and drug makers. Part of this resistance comes from the fact that antibiotics do enhance feed conversion ratios, thus lowering costs for producers.
Scientists are now finding that the changes in the bacterial community that are selected by antibiotics help the animals to glean more calories from their food. We may be able to harness the growth-enhancing benefits through other technologies such as probiotics, rather than using antibiotics. Clearly more research is needed to develop these approaches and to understand how best to limit the spread of antibiotic resistance on farms.
In the meantime, several other countries have already banned the non-therapeutic use of antibiotics in agriculture, and this may soon affect U.S. export markets for livestock and poultry products.7 comments on this story
A recent federal court decision may require the FDA to act on its own law, but Congress may need to back it up with legislation. Rep. Louise Slaughter of New York's 28th District has reintroduced HR965, the Preservation of Antibiotics for Medical Treatment Act, or PAMTA, which would restrict the non-therapeutic use of clinically important antibiotics in the livestock industry.
If enacted, PAMTA would slow the spread of antibiotic resistance, improve the health of livestock and consumers and ensure that world markets remain open to U.S. meat exports for future generations of farmers and ranchers. PAMTA is currently under further committee review and may soon come to the House floor for a vote. Wouldn't it be wonderful if this bill could receive the support of Utah's representatives?
David Erickson works in the Department of Microbiology and Molecular Biology at Brigham Young University.