What do recent regulatory and consumer actions portend for the future of existing and new animal antibiotics?
If it weren't so true, antibiotic resistance in livestock would be a great plot for Steven Spielberg's next science fiction thriller. A heroic team of veterinarians and physicians takes on an epidemic of untreatable infections caused by Superbug. Meanwhile, lawyers representing consumer activists, pharmaceutical companies, food suppliers and livestock producers battle it out in court.
Though it's not coming to a theater near you, the real-life drama of antibiotic resistance is being played out on a stage of public perception. Livestock antibiotic use as we know it is being threatened.
At issue is concern that livestock antibiotics are creating antibiotic-resistant pathogens - resulting in the risk that humans could become infected with germs that resist treatment.
Consequently, some people are calling for a ban on some or all antibiotic use in agriculture.
Livestock producers in the U.S. rely on antibiotics to maintain healthy animals and ensure the safety of the nation's food supply. But, there's a growing argument that antibiotic use in livestock is creating a public health threat.
Abigail Salyers, University of Illinois microbiology professor, says the public is realizing that many of the antibiotics widely used in agriculture are the same antibiotics being used to treat humans. Some say this increases the accumulation of drug-resistant germs, which are making once-treatable diseases incurable - especially in children, the elderly and people with weak immune systems. That, she says, makes it difficult to defend unrestricted use of antibiotics in agriculture.
"Like it or not, the use of antibiotics in agriculture is going to come under increasing scrutiny from people who may not have the farmers' best interests at heart," she says.
Despite the Food and Drug Administration's (FDA) stringent requirements on antibiotics, scientific data about antibiotic resistance is sparse. And the risks of using antibiotics in livestock haven't been adequately assessed, says veterinarian John Waddell, Sutton Veterinary Clinic, Sutton, NE.
Representing more than a dozen federal agencies interested in antibiotic resistance, the Interagency Task Force on Antimicrobial Resistance recently drafted a strategy, timetable and budget for addressing the issue. The Draft Action Plan includes 87 action items focusing on surveillance, prevention and control, research, and product development. (You can request a copy of this draft by visiting www.cdc.gov/drugresistance/actionplan/planrequests.htm.)
Part of the task force is the Center for Veterinary Medicine (CVM) - the FDA division that regulates the manufacturing and distribution of food additives and drugs given to animals. The CVM is studying the health risks posed by the use of antibiotics in food-producing animals. It is meeting publicly in January to discuss the establishment of resistance and monitoring thresholds in food-producing animals and to seek scientific input from experts. In addition, the FDA is examining all agricultural antibiotic use.
But, regardless of what scientific resolutions may surface from these efforts, the issue is bound to impact livestock production practices.
What's at Stake? Government and consumer actions put the availability, distribution, regulation, monitoring and uses of existing and new animal antibiotics into question, Waddell says. A shift toward shortening the life span of approved antimicrobials is already under way.
Fluoroquinolones, for example, may soon be off the market. Though the FDA approved these antimicrobials for poultry and cattle in the mid-1990s, in October the administration proposed a ban on fluoroquinolone use in poultry. This proposed ban is the government's first attempt to pull a drug to combat infections that have grown resistant to antibiotics.
Also at stake are subtherapeutic or growth-promotant antibiotics, fixed dose combinations, over-the-counter availability and use under the Animal Medicinal Drug Use Clarification Act, also known as "extra-label" use. The export market and research and development funds for the animal health industry are also on the table, Waddell says.
But is banning antibiotics really the answer? University of Kentucky (UK) swine nutritionist Gary Cromwell contends that a ban won't effectively combat the problem. In a UK study, Cromwell and his colleagues found swine that had no exposure to antibiotics for more than 25 years still had a large proportion (30-70%) of antibiotic-resistant enteric bacteria.
He concludes that animal age, housing system and moving stress affect antibiotic resistance just as much as antibiotic withdrawal does.
Alternatives to a Ban Instead of a ban, one possibility is antibiotics that are completely synthetic, says University of Illinois food science professor Bruce Chassy.
"Those are the antibiotics that probably show the greatest promise for the future because we've just about run out of all the (natural) antibiotics that we have," he says.
Biotechnology could be another option.
"It may help us develop other strategies in disease control - probiotic organisms that are even more effective, more disease-resistant animals, and even - by manipulating the physiology and biochemistry of the animals - more efficient animals," Chassy says.
No matter what might be ahead, Chassy says producers need to better understand antibiotic resistance and what drives consumers.
Likewise, Waddell asks veterinarians and producers to take responsibility and become more aware of issues relating to the proper use of antibiotics.
Given the amount of jargon surrounding antibiotic use - terms like therapeutic use, approved use, rational use, extra-label use, judicious use, production use, prohibited use, prudent use and use under the Animal Medicinal Drug Use Clarification Act - the issue can be confusing.
Whatever you call it, Waddell says, proper use basically means antibiotics should be used "for proven clinical indications, only when indicated, at the appropriate dosage regimen, for as long as necessary and for as short as possible." It also involves proper identification of treated animals and proper storage and handling, he adds.
While producers, regulatory agencies and pharmaceutical companies play a part in the proper use of antibiotics, the veterinarian has ultimate responsibility, Waddell says.
In addition to better understanding judicious use, Waddell urges producers and veterinarians not to concede the use of antibiotics in livestock without demanding good science.
"We cannot let emotionalism and sensationalism replace good science and judgment," he says.
Advocates of a ban on antibiotics in livestock are passionate, and they want zero tolerance of risk, Waddell notes.
"If we don't stand up as producers and as veterinarians," he says, "we're not going to keep back this stampeding herd."
In case the time comes when antibiotics aren't available, researchers are studying possible alternatives.
With a $600,000 USDA grant, researchers at Iowa State University (ISU) are exploring alternatives to swine antibiotics.
One ISU project looks at probiotics, which encourage the growth of "friendly" bacteria to prevent disease-causing bacteria from getting out of control. Preliminary studies show salmonella was reduced in young pigs fed milk containing Lactobacillus, a bacterium taken from the pigs' intestinal tracts. Researchers plan to repeat the tests in older, market-ready pigs.
"If the results are positive, farmers could decrease salmonella levels in their animals by using the method two to three weeks before the pigs are marketed," says ISU microbiologist Hank Harris.
The focus of another ISU project is bacteriophages - viruses that infect and kill bacteria. Early results show pigs given bacteriophages orally or by injection have less salmonella than other pigs. Researchers say producers might be able to dose pigs with bacteriophages hours before they are processed at the packing plant.
If these alternatives prove promising, ISU will train producers, veterinarians and processors on how to implement them.
Pork producers in the U.S. may need to prepare to discontinue use of growth-promotant antibiotics, says South Dakota State University animal scientist Hans Stein.
He points to the European Union (EU) where all but four growth-promotant antibiotics were banned in 1999. Sweden banned all growth-promotant antibiotics in 1986.
In Denmark and Sweden the ban on growth-promotant antibiotics has meant significant economic losses due to increased mortality rates and decreased daily gains in nursery pigs. For Danish pork producers the cost is more than $1 (U.S.) per pig produced, Stein says.
Discontinued use has decreased the total use of antibiotics, but it has increased therapeutic antibiotic use and the incidence of post-weaning diarrhea. It is a serious problem for nursery pigs - their mortality increased by as much as 60% in Sweden, and their daily gain decreased by 0.665 oz./day in Denmark. So far, though, grow-finish pigs show no significant changes in performance or disease pressure, Stein says.
What led to such dismal results for producers, Stein says, was that policymakers in Europe based their regulatory actions on what's known as the "precautionary principle," which boils down to "when in doubt, don't." U.S. veterinarians and producers prefer science as the arbiter.
Europe's experience, however, shows that "the press can create more decision-making than many scientific experiments," Stein says.
University of Illinois food science professor Bruce Chassy agrees. As an example, he points to how a few well-organized opponents of biotechnology have steered policy decisions.
"If you scare consumers, there is going to be a consensus to change the policy," he says.
It's hard to say how the antibiotic debate might transform production practices in the U.S. But, Stein is certain consumer demand for products from animals not fed growth-promotant antibiotics will grow.
One leading producer in the antibiotic-free niche is du Breton Natural Pork, Quebec, Canada.
Du Breton has developed preventive methods to reduce animal stress and lower the incidence of sickness, says Fresh Ideas Group, a Boulder, CO-based public relations firm that represents du Breton. These preventive methods include:
- allowing more space per animal;
- giving animals more access to fresh air and sunlight; and
- using alternative remedies like homeopathics.
Du Breton acknowledges that preventive medicine alone won't keep all animals completely healthy, so when an animal gets sick, veterinarians quarantine it and care for it with fluids, aspirin and rest. If it needs more intensive attention, it's removed from the herd. If it's then treated with antibiotics, it doesn't return to the farm.
Not surprisingly, these methods are more expensive for the producer. But, du Breton maintains this investment can be profitable in the long-term because of growing consumer interest in antibiotic-free livestock.