Understanding antibiotic resistance
Jan. 18, 2012
by Bryan Salvage
Does antibiotic use in animals cause antibiotic resistance in humans? Opinions are strong in both pro and con camps. Many natural and organic processors, plus executives in the public health community, believe overusing antibiotics – and even normal use in food-animal production – contributes to creating antibiotic-resistant strains of bacteria. But many other industry experts disagree.
“It is impossible to determine to what extent, if any, the problem [of antibiotic resistance] is related to antibiotic use in food animals,” explains James Marsden, Ph.D., Regent’s Distinguished Professor of Food Safety and Security, Kansas State Univ., associate director of the Biosecurity Research Institute located at KSU, and North American Meat Processors Association senior science advisor. “If the link could be proven, the government would have already acted to ban the sub-therapeutic use of antibiotics.”
Strong emotions and conflicting views exist regarding antibiotic resistance – which is a very complex and not a black-and-white issue, says Ashley Peterson, Ph.D., vice president of science and technology with the National Chicken Council. As a result, it is critical that policy actions regarding the use, limited use or non use of antibiotics in food-animal production be based on science, she says.
More data is needed in this debate, the Government Accounting Office (GAO) said in September. GAO urged the US Dept. of Agriculture and the Food and Drug Administration to work with livestock and poultry producers to collect more detailed information on antibiotic use in food animals. Both agencies need to improve their sampling of antibiotic use in food animals and retail meat products, GAO added.
“Without detailed use data and representative resistance data, agencies cannot examine trends and understand the relationship between use and resistance,” GAO stated in a report requested by Congresswoman Louise Slaughter (D-NY), senior Democrat on the House Rules Committee and longtime advocate of tighter restrictions on the use of antibiotics in food animals.
Chicken products marketed as “antibiotic-free” are making headway in the US. Chicago Public Schools began serving local chicken raised without antibiotics to more than 300,000 students at 473 schools on Nov. 1. The district’s new program includes approximately 1.2 million lbs. from Amish farms that don’t use antibiotics, for a total of approximately 2 million lbs. of fresh chicken in the 2011-12 school year. Students will be offered bone-in chicken two to three times per month.
No other district in the US is serving antibiotic-free poultry regularly at this level. CPS’ large purchase of chicken grown without antibiotics is being made through foodservice provider Chartwells-Thompson Hospitality. Whole Foods Market “is thrilled” to be a part of this initiative, said Rich Wolff, Midwest region meat coordinator with Whole Foods Market, at the time of the announcement. Whole Foods’ product is sourced from Miller Poultry, which produces the chain’s Pine Manor antibiotic-free chicken.
Last January, Safeway Inc. launched its Open Nature line of 100 percent antibiotic-free, natural foods, which includes fresh chicken and chicken sausages.
An agreement was forged in September between Premier healthcare alliance and Murray’s Chicken, South Fallsburg, NY, which gave hospitals and other institutions access to Murray’s antibiotic-free chicken products starting Oct. 1. Members can access these products through US Foodservice, Premier’s primary distributor.
“As much as possible, we’d like to support producers whose practices do not further jeopardize the continued effectiveness of antibiotics,” said Nancy Mulvihill, vice president of corporate communications for Covenant Health Systems and head of Covenant’s Environmental Committee, during the announcement.
Antibiotics are a valuable tool in preserving animal health and in producing wholesome food for the consuming public, counters NCC’s Peterson. “In the US chicken industry, antibiotics are used sparingly – keeping with the principles of judicious use.”
All antibiotics used to keep chickens healthy have been approved by FDA as safe and effective, and all usage is under the direction of a veterinarian and in accordance with strict regulations from FDA, she adds.
“The standards and process for reviewing an antibiotic to be used in animals is similar to the process for an antibiotic used in humans – but even more stringent in some respects,” Peterson says.
The sponsor has to show that meat from animals treated with the antibiotic will be safe for human consumption, among many other requirements. In addition, antibiotics to be used in food animals must undergo a review process to measure the risk of antibiotic resistance arising in humans as a result of the use of that product. Products currently on the market are also being reevaluated using this process.
Antibiotics aren’t always used in chicken production, and most antibiotics used in poultry production are not used in human medicine. Therefore, they do not represent any threat of creating resistance, Peterson says.
Some figures used to estimate the amount of antibiotics given to US chickens inaccurately include coccidiostats, which are unique veterinary products given to poultry to keep them from being internally colonized by parasitic organisms called coccidian, she adds. These are microscopic organisms that are protozoa, not bacteria. While some coccidiostats are classified as antibiotics due to their mode of action, most aren’t.
“None of the coccidiostats have any place in human medicine, and they are not relevant to the topic of antimicrobial resistance,” Peterson says.
Chicken meat does not contain antimicrobial residues, she adds. All chicken produced in the US is inspected by USDA inspectors who test meat samples for chemical and antimicrobial residues. All meat must be in compliance with USDA standards. Chicken consistently has among the best record of any product tested by the government, she says.
USDA states more than 242.6 million turkeys are processed annually in the US, says Sherrie Rosenblatt, vice president of marketing and communications with the National Turkey Federation. Antibiotics have been safely used on-farm along with other animal drugs for more than 50 years to treat and control disease in animals and to improve the animal’s overall health allowing for greater productivity, she says.
“The use of antibiotics helps maintain an affordable food supply and makes it more healthful and safer for human consumption,” she adds.
Antibiotics are used primarily for therapeutic reasons to treat bacterial infections, Rosenblatt says. Therapeutic doses are used for short periods of time to treat active disease infection. Antibiotics may be used sub-therapeutically, or at low levels, to control bacterial disease and improve an animal’s ability to absorb nutrients.
Antibiotics may also be used to help animals gain weight more efficiently by controlling the bacteria that can interfere with their ability to absorb nutrients, produce poisons that impair growth and cause low-grade or chronic disease that under certain conditions can become acute diseases. The amount of antibiotic in medicated feed is less than 2 oz. per ton of feed (.00625 percent).
“Without antibiotics, animal suffering would increase and animals would be more likely to contract diseases that could be passed from animals to people through the food chain,” she says.
The FDA’s Center for Veterinary Medicine (CVM) is required by law to approve all antibiotic drugs for safety and efficacy, she continues. Specific regulations govern their safe use and proper withdrawal period. USDA’s Food Safety and Inspection Service monitors residues of antibiotics or other medications. FSIS samples flocks of turkeys at random to test for violative residues. For more than 10 years, the turkey industry has been 100-percent compliant with no antibiotic residues found. Animals testing positive for residues cannot go into the food supply.
Healthy animals are needed to produce healthy food, Rosenblatt says. Research shows antibiotic use can reduce the amount of pathogens on meat, reducing the pressure on other methods used during and after processing. “Policymakers should focus on interventions to reduce foodborne pathogens rather than focusing on resistant pathogens,” she adds.
Huron, SD-based Dakota Provisions slaughters and processes 4.9 million turkeys per year and follows a strict antibiotic-use policy.
“Antibiotics are sometimes necessary in today’s growing environment to ensure the reduction/elimination of pathogenic bacteria and provide health care for our animals,” says Ken Rutledge, president and CEO of Dakota Provisions. “Antibiotic use should be limited to treatment as needed, not for prevention of illness.”
Vaccines, probiotics, effective water treatment, investment in good growing facilities and sound management practices are essential to minimize the use of therapeutic treatments, he adds. His company’s producers document all treatments prior to processing to ensure its flocks comply with necessary drug withdrawal regulations, Rutledge says.
Dakota Provisions’ objective is to provide a great, wholesome product every day, he adds. “That is, in part, accomplished by providing the judicious use of antibiotics necessary to our birds as needed,” he says.
The Defense Advanced Research Projects Agency recently recommended antibiotics be replaced with alternative technologies, such as nano-particles designed to provide for more specificity in dealing with microbiological pathogens, KSU’s Marsden says. But science, so far, indicates such a move isn’t necessary.
“There is no scientific evidence that antibiotic use in animals causes antibiotic resistance or infections in humans and there is no scientific evidence that eliminating the use of antibiotics in animals will prevent antibiotic resistance,” NCC’s Peterson concludes.