Our Work

The Problem

Antibiotic Resistant Bacteria in Animals

Pigs and other industrial farm animals are commonly given low doses of antibiotics and related drugs in their daily feed.

In the United States, food animals - poultry, swine and cattle - are routinely fed antibiotics and related drugs for disease prevention and growth promotion. Recently, major increases in antibiotic-resistant bacterial infections in human populations have led to public health concerns regarding antibiotic use for nontherapeutic purposes (i.e., not used to treat disease) in animals destined for food production.¹

Bacteria are able to develop antibiotic resistance when exposed to low doses of drugs over long periods of time. To promote growth and weight gain, entire herds or flocks of farm animals are routinely fed antibiotics and related drugs at low levels in their feed or water — a practice that has been identified as a major contributor to antibiotic resistance.² In addition, the crowded and often unhygienic conditions of many industrial farms facilitate transfer of bacteria and infection, increasing the need for antibiotic use in the hopes of preventing diseases that might arise from these conditions.

Because there are currently minimal regulations in place requiring drug manufacturers or food animal producers to report how antibiotics and related drugs are marketed and used in food animal production, the scale of antibiotic use in food animals is unknown. Poor data on animal drug production, distribution and resistance unnecessarily contribute to the risks associated with developing resistant diseases in animals and humans.

Unnecessary Human Health Risk

Broiler chickens (above) and laying hens (below) are conventionally kept in crowded sheds or battery cages in conditions which contribute to the rapid spread of contagious diseases.

During the late 1990s, the same resistant strains of Campylobacter bacteria, one of the most common causes of diarrheal illnesses in humans, were discovered in chickens and humans.³ Both kinds of bacteria were resistant to fluoroquinolones — a class of antibiotics of important use in human medicine.

Prior to 2005, farmers also used fluoroquinolones on chicken flocks for prevention and treatment of respiratory disease. Often, whole flocks received the antibiotics indiscriminately through drinking water, which quickly led to the development of resistant bacteria.⁴ Through molecular subtyping, researchers were able to trace the resistant bacteria found in humans back to poultry.⁵

Earlier studies in the 1980s linked multi-drug resistant salmonella infections in humans to exposure to cattle on dairy farms.⁶ Further studies and molecular subtyping found rapidly growing, widespread emergence of resistance in salmonella infections in humans in the U.S., which researchers concluded were likely from food animals.⁷

Unnecessary Risk, Little Gain
Although the use of fluoroquinolones in poultry was banned in the U.S. in 2005, the vast array of antibiotics and related drugs that are still used in food animals continue to pose a threat to human health. A joint report by the U.N. Food and Agriculture Organization (FAO), the World Organization for Animal Health (OIE) and the World Health Organization (WHO) found that the use of antibiotics and related drugs in humans and animals places individuals at increased risk for infection, higher numbers of treatment failures and increased severity of illness.⁸

These impacts on human health can result in both higher frequency and longer duration of hospitalizations, raising the cost of healthcare. A recent study found that antibiotic-resistant bacteria generated $16 to $26 billion dollars per year in extra costs to the United States healthcare system.

The overuse of antibiotics and related drugs in food animals is leading to increased risk of human illness and increased healthcare costs, with little to no agricultural economic benefit. Recent economic analysis of antibiotic use in poultry disputes the myth that using drugs nontherapeutically results in large economic gains. In fact, data show that improving management of farm animals (e.g., cleaning facilities more thoroughly and frequently) achieves the same benefits as nontherapeutic antibiotic use.¹⁰

Flow chart: Pathways for Transferring Antibiotic Resistant Bacteria from Farm Animals to Humans

The Solution

Improving Oversight of Drug Use and Decreasing the Threat to Human Health

Because of poor regulations and oversight of drug use in industrial farm animals, consumers in the U.S. do not know what their food is treated with, or how often. Nor is there a system in place to test meat for dangerous antibiotic resistant bacteria. In order to limit the development of antibiotic resistance in farm animals, and the unnecessary threat it poses to the public, the use of antibiotic drugs in poultry and livestock must be more carefully regulated and monitored. Congress should begin tackling the problem by reforming reporting and monitoring requirements for drug manufactures and food producers, and by curtailing the nontherapeutic use of antibiotics and related drugs in animals.

Legislation to Address the Problem

In August 2008, the President signed legislation passed by Congress to reauthorize and amend the Animal Drug User Fee Act (ADUFA), a law that grants FDA authority to collect fees for animal drug applications. The amendments require drug makers to report at the same time annually the amount, strength, dosage and intended purpose of antimicrobials used in food animals. This is an important first step in improving data collection on the use of antibiotics and related drugs in industrial farming. More should be done to curb nontherapeutic use of the drugs and help improve monitoring and response to human health threats.

PAMTA: The late Senator Ted Kennedy (D-MA) along with Senator Olympia Snowe (R-ME) and U.S. Representative Louise Slaughter (D-NY) introduced legislation – the Preservation of Antibiotics for Medical Treatment Act (PAMTA, H.R. 1549/S. 619). PAMTA would withdraw the use of seven classes of antibiotics vitally important to human health from food animal production unless animals or herds are sick with disease or unless drug companies can demonstrate that their routine use does not harm human health.

For more information, see Pew's fact sheet, "Antibiotics in Food Animal Production: A Comparison of Proposals for Reform" (PDF).

1 U.S. General Accounting Office (GAO). 2004. Report to Congressional Requesters No. 04-490, "Antibiotic Resistance: Federal Agencies Need to Better Focus Efforts to Address Risk to Humans from Antibiotic Use in Animals."

2 For more information on antibiotic resistance, please see Pew's factsheet titled: "Antibiotic Resistance and the Industrial Animal Farm."

3 GAO, 2004, Op cit.

4 Keep Antibiotics Working, "In Depth: Fluoroquinolones: Unnecessary Risks," accessed 7/1/08.

5 Smith, K.E, et al. 1999. Quinolone-resistant Campylobacter jejuni infections in Minnesota, 1992-1998. New England Journal of Medicine. 340(20): 1525-1532.

6 O'Brien, T., et al. 1982. Molecular epidemiology of antibiotic resistance in Salmonella from animals and human beings in the United States. New England Journal of Medicine. 307(1):1-6.

7 GAO, 2004, Op cit.

8 UN FAO, OIE, and WHO, "Joint FAO/OIE/WHO Expert Workshop on Non-Human Antimicrobial Usage and Antimicrobial Resistance: Scientific Assessment," Presented in Geneva, Switzerland, Dec. 1-5, 2003.

10 Graham JP, Boland JJ, Silbergeld E. "Growth promoting antibiotics in food animal production: an economic analysis." Public Health Rep 2007; 122:79-87; and Miller GY, Algozin KA, McNamara PE, Bush EJ. "Productivity and economic effects of antibiotics use for growth promotion in U.S. pork production." Journal of Agricultural and Applied Economics 2003; 35:469-482.