The growing problem of antimicrobial resistance

On April 7, 2011 the World Health Organisation (WHO) celebrated its birthday, designated World Health Day. The WHO theme for this year is antimicrobial resistance (AMR), focusing on the growing threat of a return to the pre-antibiotic era, when millions of lives were lost annually to infection by bacteria that could not be killed (1). In the European Union (EU) drug resistant infections are estimated to cause more than 25 000 deaths and generate health care costs of 1.5 billion euros annually (2). Since 2009, the EU has used European Antibiotic Awareness Day on November 18 each year to promote the prudent use of antimicrobial drugs. Canada became a part of this movement in 2010 and a transatlantic alliance with the United States has been established to jointly address the AMR problem.

We have probably become so used to these warnings that we shrug them off. The warnings began in earnest in 1969, when The Swann report on the use of Antibiotics in Animal Husbandry and Veterinary Medicine was issued (3). One of its recommendations was that the only antimicrobials that should be permitted as growth promotants in animals were those that were not depended on for therapy in humans or whose use was not likely to lead to resistance to antimicrobials that were important for treating humans. Antimicrobials such as tetracyclines, penicillin and tylosin were identified as agents that should no longer be used as growth promoting agents. This goal has long been achieved in Europe in which all growth promoting antimicrobials have been banned from animal feeds and all veterinary drugs require a prescription. However, the WHO now warns that the pace of development and spread of highly drug resistant bacterial pathogens has quickened at a time when the pipeline for developing new antimicrobials is practically empty and the prospects for new antimicrobial agents are poor (1).

The WHO is appropriately involved in increasing awareness and developing policies as this issue is truly a global one. This is illustrated by the recent emergence of gram-negative bacteria carrying the NDM-1 (New Delhi metallo-beta-lactamase-1) gene and its detection in Canada (3). These bacteria are mostly Escherichia coli and Klebsiella pneumoniae but include other Enterobacteriaceae. They possess a plasmid that confers resistance to all beta-lactam antibiotics (including carbapenems such as imipenem) except aztreonam and are also resistant to almost all other antibiotics. These bacteria appear to have originated in India and spread worldwide in a matter of months. Interestingly, the NDM-1 bacteria recently identified in 1 of 2 patients in Ontario were acquired locally (4).

The emergence of drug resistant bacterial populations is related to the use of antimicrobial agents for any reason. Elimination or reduction of underuse (associated with inadequate dose or duration), misuse (poor selection) and abuse (unnecessary use) can go a long way to extending the useful lives of these valuable drugs. The WHO article (1) notes “the massive routine use of antimicrobials, to promote growth and for prophylaxis, in the industrialized production of food” and that “in several parts of the world, more than 50% in tonnage of all antimicrobial production is used in food-producing animals.” On World Health Day, the WHO issued a policy package that includes calling on countries to commit to a comprehensive funded national plan, to strengthen surveillance and laboratory capacity, to regulate and promote rational use of medicines, to enhance prevention and control of infections, and to support innovations and research and development.

Canada has been doing its part through the surveillance activities of the Public Health Agency of Canada and veterinary diagnostic laboratories, research, education, and promotion of awareness. The CVMA, representing Canada’s veterinarians, has taken a leadership role primarily in the development of prudent use guidelines for various animal species. The CVMA has a prominent role to play in an upcoming national conference: “Antimicrobial stewardship in Canadian agriculture and veterinary medicine conference: How is Canada doing and what needs to be done?” that will take place in Toronto October 30 to November 2, 2011. Details about the conference are available on the Web site (www.antimicrobialcanada.com). A recent article in the medical journal Lancet notes that “we have watched too passively as the treasury of drugs that has served us well has been stripped of its value” (5). There is a need for veterinarians across the full spectrum of careers to intensify our efforts to be good stewards of these miracle drugs.