Turning the tables on antimicrobial resistance

The role of quality assurance programs

To prevent contributing to resistance in Canadian livestock production, we should be developing appropriate guidelines for quality assurance programs and then using those guidelines. In Canada, the Pork Quality Assurance Program is a good example of where livestock production has provided leadership in this area. The principles of this program are based on judicious drug use, which is a useful approach to manage resistance.

Programs like this outline some of the things we should be doing. We should be using Canadian approved products - ones that have gone through our risk assessment process. Veterinary-prescribed product should be used by producers as directed and products to which producers have access should be used according to the label, and records should be kept on all use. Certainly the importance of record keeping can be seen in today's world. It gives the ability to improve our management and trace things back if there is a problem.

Along with prudent use, there needs to be a real focus on good husbandry and good biosecurity practices. Nobody likes to use antimicrobials unnecessarily, but the fact of the matter is that we need them to manage and treat disease for many different reasons, including animal health and welfare, along with the safety and protection of food, consumers and the environment. Good quality assurance programs offer excellent guidance for responsible use.

Advances in testing

There are two main fronts for checking proper use of antimicrobials: chemical and microbial.

On the chemical side, one of our biggest checkpoints in Canada has been Meat Hygiene and Residue Testing Program. It's a chemical testing program administered by the Canadian Food Inspection Agency. I often call the program inspectors the Maytag repair men - always there, ever vigilant, but finding no harmful residues because veterinarians and producers use products responsibly.

On the microbial side, the checkpoints are less prominent. In its quality assurance program, the pork industry has shown a lot of leadership relative to the use policy by saying that producers should work with their veterinarian and use Canadian approved medications. Initiatives like this, along with continued assessment and action, are a good approach.

Another positive initiative is phasing out the use of active pharmaceutical chemical ingredients. Standards or guidelines are being developed for pharmacy and veterinary compounding of animal drugs.

Comparing Canada to the world

In the global picture, Canada is doing well in managing the antimicrobial resistance issue. Certainly some of our regulatory policies need updating, but there are several areas where other countries are still far behind us.

In one area, the World Health Organization is saying we should be looking at doing risk assessments on products such as antimicrobial growth promotants. The European Union response has been to ban a number of growth promotants. Canada has decided that rather than ban certain growth promotants outright, we will go through and reevaluate our products to ensure that they are efficacious and meet safety criteria. I think this is a good decision.

In looking at areas for improvement, Canada is in the process of developing a national surveillance system for antimicrobial resistance, for the major food-borne pathogens affecting food animals. We need to document the prevalence of resistant bacteria in food animals so that we can develop mitigating strategies that minimize the impact of major food-borne organisms that might have an impact on human health. There is also the need for an increase in producer participation in quality assurance programs that require producers to use antimicrobial products according to their specs. Consideration may be given to limiting extra-label use of certain products, similar to the U.S.

Overall, everybody is struggling to manage the microbial situation and in general Canada has a good reputation, but we have to make sure we don't fall behind and we must be proactive.

The double-edge of product use

It's important to realize that how to manage the use of products isn't a black and white issue, and there are many interesting cases that arise. In Britain, some of the growth promotants that had been restricted were recently reintroduced. Basically, the industry found they were having so many enteric problems without the products that they decided to bring them back. This is typical of other European cases, and to me it illustrates the problem of regulatory policy not recognizing the consequences of it relative to needs. The bottom line is, if veterinarians and producers didn't think there was a benefit to antimicrobials, they wouldn't use these expensive inputs. In addressing the resistance issue, we also need fall back options to avoid losing ground in animal health and raising new public health issues.

Obviously one of the primary concerns with antimicrobial use and resistance in food animal production is that the resistance built up in animal use could be transferred to humans. This is why today new drugs are evaluated based in part on resistance transfer potential. But on the flipside, it's important to remember there's also a human health connection if some of these drugs are not approved or are removed from use. For instance, a recent U.S. study showed that following the ban of antimicrobial product for poultry, bacterial contamination in the food processing chain increased. The birds were less healthy, and that led to human health concerns.

Along with evaluating whether a drug is high or low risk for resistance transfer, there's also evaluation of whether the drug has use in human medicine or if there is a related drug used in human medicine. Those evaluating new drug products then have to categorize the drugs relative to risk. Drug sponsors doing risk assessment have traditionally focused on toxicology, which means applying maximum residue limits or tolerances for antimicrobial drugs as a means of managing risk. However, experience around the world has shown that the common approach to analysing risk associated with antimicrobial products needs to be advanced. And, instead of assessing only the consequences of using these products, maybe we should also be assessing the consequences of not using them.

The availability factor

In animal health, everyone is looking for alternatives to antimicrobials. But, indications are we don't have enough alternatives currently available to switch from antimicrobials and continue on with the livestock production practices we have now. There is a lot of research going on to develop vaccines to prevent disease, so we don't have to treat diseases with antimicrobials. There is also a lot of research in the area of probiotics - using probiotics, not so much to treat, but to control disease. However, we don't have alternatives available now that will have a major impact on replacing antimicrobials.

In fact, we know one of the problems out there is extra-label use of existing drugs, and one of the reasons for this is low drug availability. We need to look at drug availability from several perspectives. From the perspective of prudent use, we have to use products according to label. That means we need products with specific use guidelines. We also need products that can be used in rotation, to help prevent the buildup of resistance.

One of the contributing factors to the low drug availability is that, within the Canadian animal health industry, most pharmaceutical companies are backing off of R&D as it relates to food animal product investment. This is partly because we have limited predictability in our review process for new food animal drug products. Canada is behind a lot of other countries in the world in approvals for new drugs. It's hard for pharmaceutical companies to get excited about an investment that is going to take a minimum of 10 to 12 years of development and cost $250 to $500 million, not knowing when they'll get a return on their investment by having a product in the marketplace.

The cost factor for producers also has to be considered in dealing with this issue. If we look at the European experience, the banning of growth promotants increased the production costs for pork producers by $2 to $5 per hog. That's a very challenging situation for anyone who wants to be competitive in the international market.