What do recent regulatory and consumer actions portend for the future of new and existing animal antibiotics?

If it wasn'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 in court.

Though it's not coming to a theater near you, the real-life drama of antibiotic resistance is being performed on a stage of public perception.

At issue is concern that livestock antibiotics are creating antibiotic-resistant pathogens that could put humans at risk. As a result, there's a call to ban some or all antibiotic use in agriculture.

Livestock producers in the U.S. rely on antibiotics to maintain healthy animals and ensure the nation's food supply is safe. 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 cross-select for resistance to front-line, human-use antibiotics. Children, the elderly and people with weak immune systems are most at risk.

"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 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.

Regardless of what scientific resolutions may surface from these efforts, the issue is bound to impact livestock production practices. (See "Antibiotic-Free Carries a Hefty Price Tag,".)

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.

For example, fluoroquinolones may soon be off the market. Though FDA approved them 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. FDA is now reviewing fluoroquinolone use in cattle.

Also at stake are subtherapeutic or growth-promotant antibiotics, fixed dose combinations, over-the-counter availability and "extra-label" use. The export market and research and development funds for the animal health industry are on the table, too, Waddell says.

But is an antibiotic ban 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 age, housing system and moving stress affect antibiotic resistance just as much as antibiotic withdrawal does.

Effective Solutions?

So if a ban isn't the answer, what is? One possibility, says University of Illinois food science professor Bruce Chassy, is antibiotics that are completely synthetic.

"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.

Another part of the answer might be biotechnology.

"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.

Despite 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 - i.e., 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 - it can be confusing.

Whatever you call it, Waddell says, proper use basically means antibiotics should be used "for proven clinical indications, 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 for proper use, 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."

How the threat of antibiotic resistance could transform production practices is anyone's guess. But, Horizon Organic, Longmont, CO, a leading producer of organic dairy products, may provide a glimpse.

Horizon Organic 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 Horizon. These preventive methods include:

- allowing more space per animal,

- giving more access to fresh air and sunlight, and

- using alternative remedies like homeopathics.

Horizon acknowledges 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 and doesn't return if treated with antibiotics.

Not surprisingly, these methods are more expensive for the producer. Fresh Ideas Group reports that a Horizon dairy cow costs 40-50% more to produce than its conventional counterpart.

But, the group maintains this investment can be profitable in the long-term because of growing consumer interest in antibiotic-free livestock. Evidence of that may lie in the 46% increase in net sales ($33.4 million) Horizon reported for the fiscal 2000 third quarter.

Lessons From Europe Will the above scenario become convention? It's hard to say, but South Dakota State University animal scientist Hans Stein is certain consumer demand for such products will grow. He says U.S. livestock producers may need to prepare for more limited use of growth-promotant antibiotics.

As an example, Stein points to the European Union (EU) where all but four growth-promotant antibiotics were banned from use in 1999. Sweden banned all growth-promotant antibiotics in 1986.

What led to such stringent regulations, Stein says, was that European policymakers based their actions on 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. 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.

Policy changes based on public perception rather than science can lead to a dismal result for producers. In Denmark and Sweden the ban on growth-promotant antibiotics for pork producers has meant significant economic losses due to increased mortality rates (as high as 60%) and decreased daily gains among nursery pigs.