Veterinarians seek dialogue in debate over antimicrobial resistance

Poultry and livestock veterinarians at the antibiotics symposium sponsored by the National Institute of Animal Agriculture advocated a one health approach to dealing with antimicrobial resistance.

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The future of antibiotic use in poultry and livestock production is being shaped by FDA regulations being formulated under great public pressure to solve the problem of antimicrobial resistance in humans but with many scientific questions unanswered. Those questions include: What is antimicrobial resistance? How does it develop? From where is it originating as more human pathogens become resistant to antibiotics over time? When the presumptive answers are peeled away, much of the science is still not precisely understood.

Nonetheless, the presumptive culprit in the public debate is often, the poultry and livestock producers’ use of antibiotics in their flocks and herds. In September 2012, a New York Times headline trumpeted, “Farm Use of Antibiotics Defies Scrutiny.” While the article rightly identified a lack of data as a central hurdle to be overcome in developing an understanding of antimicrobial resistance, it pointed the presumptive finger of blame at the use of antibiotics in animal production because of its sheer volume. It’s a conclusion that for now is not scientifically supported, but one that makes for attention-getting headlines and one that is perhaps more comfortable for a public unwilling to focus on more complex answers.
The facts are scary 
Driving the headlines and emotions are fear and mistrust  and the facts are scary. Larry S. Schlesinger, MD, chair of the Department of Microbial Infection and Immunity, Ohio State University, shared this reality with symposium attendees.
“The issue of antimicrobial resistance is recognized essentially by all as a global crisis with the urgent need for new and far-reaching initiatives which is part of the goal for this conference,” he said.
“In fact, this dire situation has led to predictions of a medical catastrophe and a true return to the pre-antibiotic era. A situation, I dare say, we are starting to see today in certain sectors of the hospital  for example, the intensive care unit  with totally resistant bacteria that can no longer be treated.”
One health approach 
Veterinarians often get the blame from their counterparts in human medicine. That’s why the veterinarians who gathered for the National Institute of Animal Agriculture’s symposium, “A One Health Approach to Antimicrobial Use & Resistance: A Dialogue for a Common Purpose,” sought exactly that  a dialogue with the common purpose of starting to deal with the problem of antimicrobial resistance.
Central to the one health approach is the collaborative effort of multiple disciplines — working locally, nationally, and globally — to attain optimal health for people, animals and the environment. Not only is blame antithetical to one health, it is counterproductive to dealing with the complex problem.
What role does antibiotic use in animals play? 
“The use of antibiotics in animal production has not been shown to cause antimicrobial resistance in humans,” said Dr. Ron DeHaven, executive vice president, American Veterinary Medical Association.
“Antimicrobial use in food-producing animals can serve as a reservoir for antimicrobial resistance, and the more we expose the organisms to antimicrobials the more we give them the opportunity to develop resistance. Although that may be true in a very simplified, general sense, there is no clear scientific evidence of how and to what extent such exposure affects human health," he said.
Is anyone heeding the one health approach? 
Scientific results that don’t fit the conventional wisdom about antimicrobial resistance aren’t always popular. Dr. Stuart Reid, Royal Veterinary College, University of London, and his collaborators, compared the antimicrobial resistance profiles from S. Typhimurium DT104 isolates to determine the flow of resistance genes between humans and animals. The research included 5,200 isolates (2,761 human and 2,439 animal) collected in Scotland from 1990 to 2004.
Three questions were asked in the research:
• In which microbial population are the resistance profiles first identified?
• Are the observed profiles distributed randomly across the animal and human populations?
• Are the populations genuinely different? Is one more ecologically diverse than the other?
“Our data are telling us that the major source of resistance in humans in DT104 in Scotland is unlikely to be coming from the animal population,” Reid told the symposium.
“This research was presented at the time when the chief medical officer in the United Kingdom had just called for the withdrawal of three antimicrobials from animal usage." Referring to the response of the medical community to his research, Reid said, "It was highly contentious."
“We simply have to get beyond that and say what the data are telling us, because we are not going to get the one health solution to this problem unless we start getting out of the trenches and creating a new lexicon for dialogue.”
The Denmark experience 
A real-world experiment that seems to receive more attention in the veterinary community than in the medical community has been the prohibition of antibiotics for growth promotion or feed efficiency purposes in Denmark. Antibiotics can only be used therapeutically there.
“While the ban has been in place for quite some time, there has been no decrease in the frequency of antimicrobial resistance in humans,” DeHaven said. “Indeed, some evidence would suggest that there has been an increasing prevalence of antimicrobial resistant infections in people since that ban took place. Admittedly, there is no experimental control, so we don’t know what might have happened had the ban not been in place. It might have been significantly worse than it is now. But we do know that there has been significantly more use of antimicrobials in animals for therapeutic purposes since the ban was put in place for preventative and growth promotion and feed efficiency purposes.”
Real-world complexity deserves dialogue 
A real-world question for U.S. regulators is whether the lower doses of antibiotics being administered in more animals under current regulations is better than the higher doses in fewer animals that may be assumed to occur for therapeutic purposes under future regulations.
“It has been suggested that because the lower doses provide a continual exposure to a large number of bacteria there is a greater opportunity for resistance to develop. On the other hand, some researchers would suggest that a higher dosage will kill off all of the susceptible bacteria leaving those that are resistant to survive and no longer having to compete with those bacteria that are not resistant and thus allowing the resistant bacteria to thrive.
“With higher dosages in fewer animals, perhaps we will need stronger drugs eventually and as has been the case in Denmark where they banned the use for prevention purposes they are in fact culling more animals than they did before the ban.”
These are examples of the kinds of issues about which veterinarians are seeking dialogue with the medical community and regulators.
One health approach applies on all sides 
Schlesinger reminded the symposium attendees that the one health approach is universal in its application, applying to veterinary and medical communities and government.
“We know more than ever that the problem of human infection cannot be viewed in isolation, because it is reflective of microbes in the food chain. Population growth brings with it a continual increase in the mixture between animals, humans and the environment. In this context, it is estimated that over 60 percent of all infectious diseases of animals can also affect humans. And the incidences of new and emerging zoonotic infections are on the rise continually.
“The one health approach to antimicrobial use and resistance means developing meaningful partnerships between public health, environmental health and animal health. These partnerships are needed instead of people blaming or pointing fingers at each other,” he said.
Reid echoed what Schlesinger said and added that the one health approach must include action on the technical level, the social level and the institutional level.
“It is only when those three levels work together that we are going to be able to make a difference. We have to get a degree of urgency in our approach to the problem and be sure that we don’t fall into the trap of trying to assign blame when blame is not going to move us forward,” he said.

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