Confusion evident on human, cattle drug use

The article, Prudent antimicrobial use key to food safety, supply, in the Feb. 2, 2012, issue states, “Of course, many of the same antibiotics used for human health reasons are also vital to livestock health and production, and they are widely used in livestock to prevent and treat illness. That wide use may also mean greater opportunity for bacteria to develop resistance.”

However, not all antimicrobials are the same. In the case of beef cattle, a more accurate statement is: “many of the antibiotics that are used to prevent and treat illness in beef cattle are not vital for human health reasons.”

Antimicrobials are divided into four classes based on their importance in human medicine.

Antimicrobials classified as very high importance are used to treat very serious human infections.

High importance antimicrobials are of intermediate concern in human medicine.

Medium importance drugs are rarely used to treat serious human health issues, such as tetracycline for acne, and those of low importance, such as ionophores, are not used in human medicine at all. Antimicrobials from each category are approved for use in beef cattle, but drugs classified as high and very high importance are seldom used.

Recent research led by the Public Health Agency of Canada, Agriculture Canada, the University of Colorado and Feedlot Health Management Services found that less than 10 percent of drug doses given to feedlot cattle belonged to the high importance category, and less than one percent to the very high importance category. These calculations did not include low importance drugs, which would reduce the percentages.

The study also found that multidrug resistance and resistance to drugs of very high importance are below three percent in bacteria isolated from feedlot cattle.

Similarly, reports from the Canadian Integrated Program for Antimicrobial Resistance Surveillance (CIPARS) indicate that the prevalence of multidrug resistant bacteria and resistance to drugs of very high importance are below two percent in beef cattle arriving at abattoirs, as well as retail beef, and have not increased since the CIPARS program began in 2002.

Cattle producers have an ethical responsibility to protect the health and welfare of their animals. Antimicrobials are an important tool in this regard because not all cattle diseases can be prevented by vaccination.

Producers also have an ethical responsibility to continue to use these antimicrobial products prudently.

Producers enrolled in Canada’s Verified Beef Production on-farm food safety program follow industry-sanctioned practices that demonstrate that they select, use, store and dispose of antimicrobials in a re-sponsible manner.

We must recognize that drugs of the highest importance to human medicine are rarely used in beef cattle production. Resistance levels are extremely low in cattle and show no increase over time.

We must not confuse antimicrobials of high importance in human medicine with drugs of low importance. Generalizing the issue of antimicrobial resistance across all antimicrobials and across livestock industries contributes to the confusion among the public and officials who must balance the issues around the use of antimicrobials for maintaining the health and well-being of livestock, pets and humans.

Research and surveillance evidence suggests that restricting antimicrobial use in beef production will have clear negative consequences for the health and welfare of beef cattle with no benefit for human health.

Reynold Bergen, PhD, is the science director of the Beef Cattle Research Council, Canadian Cattlemen’s Association.

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