November 16, 2017 Liz Borkowski 5Comment

Last week, the World Health Organization released new guidelines that recommend livestock producers halt routine antibiotic use in order to combat the urgent public-health problem of antibiotic-resistant bacteria. Specifically, WHO calls for an overall reduction in livestock producers’ use of all classes of antibiotics important for human health. This includes an end to antibiotics for growth promotion, and for disease prevention when there is no diagnosis of disease susceptible to antibiotics elsewhere in the herd or flock. When animals are sick, WHO recommends they be tested to determine which antibiotics their illness responds to, and then treated with the option that WHO has classified as least important for human health.

These guidelines don’t have any enforcement authority behind them, but they could prompt countries to adopt or strengthen policies aimed at reducing the use of antibiotics in food-producing animals. STAT’s Helen Branswell writes:

But Ramanan Laxminarayan, director of the Center for Disease Dynamics, Economics and Policy, said the recommendations will help health ministries around the world make the case for banning growth promotion to agricultural ministries, which generally wield more power.

“I think the Ag ministry, left to itself, would certainly do nothing. Even pushed by the health ministry may do nothing. But pushed by the health ministry with a WHO recommendation — if nothing else, it stiffens the spine of health ministries in asking for this,” Laxminarayan told STAT.

CIDRAP’s Chris Dall notes that the news conference to release the guidelines included information about the successes some other countries have had in restricting the use of antibiotics in food animals: Denmark, for instance, has seen use of animal antibiotics drop 49% since 1994, while enjoying a 15% increase in meat production.

In the U.S., growing concern about human infections with bacteria resistant to an ever-longer list of antibiotics led to FDA guidance aimed at halting the use of antimicrobials for growth promotion in food animals. Meanwhile, consumer demand for meat raised without the routine use of antibiotics strengthened. Big Chicken author Maryn McKenna explained to Fresh Air’s Terry Gross that it was in response to consumer demand that major US chicken producer Perdue Farms began a process of phasing about antibiotics in 2007 and is essentially antibiotic-free now. And, McKenna reported, major chicken producer Tyson followed suit, and fast-food and fast-casual chains (Chick-fil-A, Subway, McDonald’s) now serve chicken raised without antibiotics. The transition will take longer for beef and pork, but US chicken producers have shown that it’s possible to transition away from routine antibiotic use and still meet this country’s large appetite.

Problematic response from USDA

Consumers and forward-thinking food producers in this country might be heading towards better antibiotic stewardship, but the Trump administration is not on board. USDA quickly issued a news release responding to the WHO guidelines:

Dr. Chavonda Jacobs-Young, USDA Acting Chief Scientist, today issued the following statement:

“The WHO guidelines are not in alignment with U.S. policy and are not supported by sound science. The recommendations erroneously conflate disease prevention with growth promotion in animals.”

“The WHO previously requested that the standards for on-farm antibiotic use in animals be updated through a transparent, consensus, science-based process of CODEX. However, before the first meeting of the CODEX was held, the WHO released these guidelines, which according to language in the guidelines are based on ‘low-quality evidence,’ and in some cases, ‘very low-quality evidence.'”

Claiming that the WHO guidelines are “not based on sound science” suggests a misreading of the WHO publication in question and a failure to appropriately weigh the strength of evidence against the public-health threats.

The full WHO guidelines document explains that the Guideline Development Group used the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach to assess the quality of the studies. The authors explain, “The GRADE approach defines the quality of the evidence as the extent to which there is confidence that an estimate of effect or association reported in the available evidence is correct.” Under this system, randomized controlled trials are initially considered high-quality evidence and observational studies low-quality evidence, and then the group considers other factors that can raise or lower the study’s ranking.

A “low-quality” GRADE ranking doesn’t mean a study is shoddy and should be disregarded; it means that confidence in its precision is low. A single study with a low GRADE ranking probably shouldn’t form the basis for major policy changes, but a lot of studies with that ranking whose findings all point in the same direction count as useful evidence. What recommendations a group then makes based on that evidence depend in large part on the severity of the threat and the potential harms of the proposed solution. The WHO guideline report addresses this specifically. Here’s what the authors write about their first recommendation (“We recommend an overall reduction in use of all classes of medically important antimicrobials in food-producing animals”), a strong recommendation with low-quality evidence:

The GDG determined that this recommendation should be strong, despite the low quality evidence, because the beneficial human health benefits (lowered prevalence of antimicrobial resistance in bacteria isolated from humans) strongly outweigh any potentially harmful or undesirable outcomes.

The evidence from the systematic reviews and narrative literature reviews reveals that restricting use of antimicrobials in food-producing animals reduces the prevalence of antimicrobial resistance in bacteria isolated from food-producing animals that are, and can be, transmitted to humans. Extensive research into mechanisms of antimicrobial resistance, including the important role of horizontal gene transfer of antimicrobial resistance determinants, supports the conclusion that using antimicrobials in food-producing animals selects for antimicrobial resistance in bacteria isolated from food-producing animals, which then spread among food-producing animals, into their environment, and to humans. Furthermore, the systematic reviews concluded that broad restrictions covering all antimicrobial classes appear to be more effective in reducing antimicrobial resistance compared to narrow restrictions of one antimicrobial class or drug, even though there are examples of marked reductions in antimicrobial resistance following restriction of a single antimicrobial.

There is enough evidence to act on this serious threat to global public health. USDA might have reasons for not wanting to adopt all of WHO’s recommended policies immediately, but they are wrong to claim the science is unsound.

5 thoughts on “WHO releases new guidelines on antibiotics in food animals; USDA muddies the waters

  1. Thanks for bringing this to our attention. When it comes to the grave threat of antibiotic resistance, erring on the side of precaution to protect the public’s health is essential. I’d love to see the email exchanges between the acting chief scientist at USDA and the White House as the prepared her written statement.

  2. Dangerous bacteria are becoming increasingly more resistant to antibiotics. Prudent use of antibiotics in livestock production is undoubtedly paramount to slow the spread of antibiotic resistance. The new guidelines released on November 7th by WHO recommend that farmers and the food industry stop using antibiotics routinely to promote growth and prevent diseases could be an effective way to curb the emergence of drug resistant pathogens. It does a good job emphasizing the urgency of the threat. Although this recommendation is an action being taken in the right direction, it will require strong enforcement to ensure compliance which leads me to question its overall effectiveness.
    The WHO’s approach has already been criticized by the Trump administration. The claim that the guidelines are” not based on sound science” or that the approach “erroneously conflates disease prevention with growth promotion in animals” are as stated by the author, a wrong claim. Merely blasting the WHO just leads me to assume that the Trump administration does not have a clear perspective of the seriousness of the issue. They could have addressed their disagreement in a manner that shows understanding, and proposed alternative preventative measures.
    The FDA has made significant efforts to reduce antibiotic use in livestock such as ending the use of medically important antibiotics for growth promotion and requiring a veterinary prescription for all medically important antibiotics used in food-producing animals.  It asks farmers not to use the drugs as a growth promoter, but supports the practice of using them to “prevent” diseases. The lines between disease prevention and growth promotion are sometimes blurred, creating a loophole for farmers to continue its use as usual. They will merely change the language they use to describe their antibiotic reliance. Meaning, although antibiotic use as growth promotor has already been restricted, WHO’s approach may be a more effective way to get rid of the loophole created by the FDA.
    WHO recommends that sick animals should be tested to determine the most effective and prudent antibiotic to treat their specific infection. Further stating that the antibiotics used in animals should be selected from those WHO has listed as being “least important” to human health. This raises many questions such as “is this ethical?” NPPC stated. “Denying pigs, cows and chickens necessary antibiotics would be unethical and immoral, leading to animal suffering and possibly death, and could compromise the nation’s food system” (USDA, Industry groups, 2017). In addition, do we even have the advanced diagnostic methods necessary for veterinarians to follow such procedures?
    Many of the questions the WHO’s recommendation leaves unanswered could be targeted in a systemic approach through implementation of different public policies. Utilizing push and pull incentives to help develop alternative therapies for treatment of livestock would be one. This will reduce the need for antibiotics by adopting non-antibiotic best practices, and by innovating new technologies, to maintain animal health and prevent disease.
    Regarding the current antimicrobial susceptibility tests, gene sequencing can identify known resistance markers but cannot predict susceptibility. Investing in technologies that can predict susceptibility will be important in expanding surveillance to detect new and emerging resistance threats. Such incentives for research and development of drugs and detection technologies can be funded through private institutions, regulatory agencies, or through taxation.
    Since profit maximization is the most important criteria in farmers’ decision of antibiotic use, accommodating incentive mechanisms can be explored. Incentives or Cash Transfers can be used to reward and promote safer practices, and sanitary environment that can keep animals from getting sick in the first place. Also, lowering the tax burdens of businesses and incentive investors in a state if they meet the restriction on antibiotic use in livestock production will lure more and more stakeholders to participate in the program.
    These incentives can also come into play to improve transparency of meat and poultry suppliers about their antibiotic use practices, about which antibiotics are being used by supplying farms, for what species, and in what quantities. This will aid to develop a unified system for collecting detailed data on the use of antibiotics at the farm level which will be important in improving regulatory policies.
    As far as policy interventions, different Price instruments can also be employed to discourage antibiotic use. Increasing the revenue of antibiotic-free production or increasing the costs of using antibiotics that will affect farmers with high antibiotic use much more than farmers with low antibiotic use could be used (Ge,2014). State and local actors can also make procurement choices to prioritize and increase the purchase of meat and poultry raised without the routine use of antibiotics in the absence of diagnosed disease and support producers that are using antibiotics responsibly. Although these approaches may increase the cost of these farmers’ products to the public, it could be an attractive approach for suppliers that could be more effective.
    At the end of the day, we must make sure that all parties involved in the cycle of resistance antibiotic feeding are aware of which antibiotics are used in food animal production, and be familiar with mechanisms of plasmid transferability, cross-selection and co-selection (Landers, 2012). It is fundamental that food producing animal and poultry industries, veterinarians, physicians, infectious disease researchers are all on the same page and know which antimicrobials are critical to human medicine to comply with the restrictions imposed by WHO. Communication campaigns could be used to stimulate compliance to such policy regulations.
    Moreover, developing a Structured communication will be essential to implement role changes leading to systemic changes. There must be public policies set so that each member of the team contributing to this global threat are functioning at the top of their scope of practice to endorse reduction of antibiotic use. Although Making teams work well in health care is difficult, working to make a collaborative team between different sectors will be significant.
    Within veterinary medicine there is widespread support for the concept of One-Health in dealing with inter-connected issues and phenomena in promoting human, animal, and ecosystem health. Embracing this One Health approach to reduce antibiotic resistance, meaning that misuse or inappropriate use of medically important antibiotics, whatever the setting, is a shared responsibility amongst physicians, veterinarians, and infectious disease researchers and the public. These are all different measures that could systemically target antibiotic misuse in livestock production.

    References
    Ge, Lan, et al. “A Bayesian Belief Network to Infer Incentive Mechanisms to Reduce Antibiotic . ..
    Use in Livestock Production.” NJAS – Wageningen Journal of Life Sciences, vol. 70-71, 2014, pp. 1–8., doi:10.1016/j.njas.2014.01.001

    Landers, T. F., Cohen, B., Wittum, T. E., & Larson, E. L. (2012). A Review of Antibiotic Use in
    Food Animals: Perspective, Policy, and Potential. Public Health Reports, 127(1), 4-22. doi:10.1177/003335491212700103

    “USDA, industry groups take issue with WHO’s latest statement on poultry, livestock antibiotics.”
    Pig Health Today, 13 Nov. 2017, pighealthtoday.com/usda-industry-groups-take-issue-with-whos-latest-statement-on-poultry-livestock-antibiotics/.

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