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promotion was also approved as a label claim on some antibiotics approved for delivery through feed or water. That’s about to become passé as pharmaceutical companies in Canada follow suit with their U.S. counterparts in voluntarily removing growth-promotion claims from therapeutic antibiotic labels. Ultimately, the goal is to achieve labelling harmony with the U.S. so that the onus isn’t on Canadian veterinarians to decide on extra-label use, Rosengren explains. Label claims on some antibiotics approved in both countries are much broader in the U.S. than in Canada because Health Canada’s tight regulations make it burdensome for pharmaceutical companies to bring new products with wide label claims to Canada. The products with the revised labels will still be available for therapeutic and preventative use. Consumers don’t understand the preventative approach because it’s not used in human medicine, she says. Beef production systems on the other hand are very predictable and often preventative use can be the most appropriate. “If I have a pen of newly weaned calves and one starts to cough, I had better be proactive or I will have a pen of coughing calves. Is it humane to let them all get sick so I can prove they needed the drug when I predictably knew the whole pen would get sick and I delayed use of the small guns and now need to go in with the big guns?” Removal of growth-promotion claims doesn’t apply to ionophores and other technologies that have gained favour over oral antibiotics for this purpose, those being hormonal ear implants and beta adrenergic agonists.
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Ionophores are classified as a polyether antibiotic, not a therapeutic antibiotic. They have never been used in human medicine, therefore have no relevance in the resistance debate, Rosengren says. In ruminants, they improve feed efficiency in several ways, one of which is by reducing the methane-producing bacteria in the rumen that waste feed energy that would otherwise be available for growth. 3. Agriculture is creating superbugs that make us vulnerable to diseases we used to be able to cure. Superbugs is a catchy word that refers to bacteria with resistance to more than one antibiotic. The World Health Organization and Health Canada have stated that antimicrobial resistance in human medicine is primarily associated with the use of antimicrobials to treat human infections. Antibiotics are one type of antimicrobial. They act specifically against bacteria, whereas antimicrobials include a broader range of substances, right down to common bleach and soap that kill bacteria, viruses, fungi or parasites. One statistic that doesn’t get much publicity comes from the U.S. Centres of Disease Control (CDC). It estimates that 20 to 50 per cent of all antibiotics prescribed in U.S. acute-care hospitals are either unnecessary or inappropriate, stating that this misuse has contributed to the growing problem of antibiotic resistance. The CDC initiated an antibiotic awareness program in 2009 to promote improved use of antibiotics in hospitals and this year recommended that all acute-care hospitals implement antibiotic stewardship programs (ASPs). Canadian hospitals are also taking this positive step. As of 2013, Accreditation Canada added ASP requirements to its program and Ontario has required ASPs for acute-care hospitals undergoing accreditation. The Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) was set up to monitor trends in antimicrobial use and resistance to 15 antimicrobials in certain bacteria from human, animal (beef cattle, chicken, pigs) and their food products. The latest results online (2011) show generic E. coli from retail ground beef as having negligible resistance to the highly important antibiotics and low resistance to the older drugs of lesser importance in human medicine. The levels of resistance to some antibiotics rise and fall through the years and in some cases were lower in 2011 than in 2003. This closely mirrored the pattern of resistance in abattoir samples taken from the beginning of the large intestine. Rosengren summarizes a 2013 CDC report on antimicrobial resistance and threats that lists 18 bacteria for which antibiotic resistance is considered to be urgent, serious or of concern. None of them have anything to do with agriculture. Only three of the serious threats relate to agriculture through foodborne exposure, and none of the threats of concern relate to agriculture. “Yes, it can be very serious if someone gets resistant bacteria from meat, but the probability of that happening in Canada is infinitely small because we have incredibly good programs in slaughter plants, good kitchens and we know how to handle and cook meat,” Rosengren says. Remember, foodborne bacteria are not resistant to heat. Proper cooking destroys them. People need to understand, too, that concern is not the same as risk, she says. It’s a long journey from farm to fork and then a resistant bacteria would have to actually cause illness and be resistant to the drug of choice for treatment. In the U.S., a risk assessment followed the chain from farm to fork and estimated that the human health impact from flouroquinolone use in dairy cattle was one case in 13 years for campylobacter and one case in 293 years for salmonella. c
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