Antibiotics in Foods

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Antibiotics belong to a category of drugs called “antimicrobials,” and include medicines like penicillin, tetracycline, and amoxicillin. These drugs are used to kill or inhibit the growth of bacteria without causing significant harm to the host (such as a human or an animal). When bacteria are able to get past natural defenses (i.e., the skin or the highly acidic stomach), some can begin to colonize their host, discharging hazardous toxins as they multiply and even when they die.


Traditional Uses

In humans, antibiotics are used to treat infections caused by bacteria, including ear and skin infections, food poisoning, pneumonia, meningitis and other serious illnesses. They are also crucial in treating infections that can complicate medical procedures such as surgery, cancer therapy, and transplants.

Traditionally, antibiotics were derived from natural compounds. Many organisms (including various species of fungi) produce substances that destroy bacteria and thus prevent infection. Penicillin, for example, is made from mould. Today, antibiotics such as fluoroquinolones are synthetic – meaning they neither occur naturally nor are they derived from natural compounds.

Since their first application many years ago, antibiotics have increased in number and variety. Today there are hundreds of antibiotics in use, though the discovery of new antibiotics has slowed significantly.

What are Antibiotic-Resistant Bacteria?

It is important to have the full course or prescribed dosage of antibiotics. Having a few antibiotic pills may actually be harmful. When bacteria are exposed to small amounts of antibiotics, the antibiotics can actually make the bacteria stronger. This is because while some microorganisms die off as a result of the antibiotic, not enough of the drug is present to kill the stronger bacteria. As a result, the stronger bacteria live on, adapt to living with low levels of antibiotics, and multiply. These stronger bacteria are called “resistant bacteria” because they have adapted to surviving with the antibiotics, and therefore antibiotics can’t kill them. As a result, traditional antibiotics are losing their effectiveness in the battle against infectious diseases. Some strains of tuberculosis, for example, have become resistant to common antibiotics.

A good example of antibiotic resistant bacteria would be Staphylococcus aureus. This is a highly pathogenic microbe that is linked to toxic shock, skin abscesses, and heart valve infections. In the United States, almost every strain of S. aureus is now resistant to penicillin, and strains of the disease have even begun to develop resistance to newer drugs like methicillin and vancomycin. The threat of prolonged illness or death from an S. aureus infection has increased as it has become more resistant and fewer drugs are able to effectively control or eliminate it.

Campylobacter bacteria are the most common cause of bacterial food-borne illness, with over 2 million such cases of "food poisoning" annually. Most Campylobacter infections do not require treatment. But of those that do, one in six (18%) are resistant to a fluoroquinolone antibiotic, the treatment of choice for food poisoning. Ten years ago, such resistance was negligible.

Although antibiotic resistance is a natural phenomenon, humans have greatly speeded up the process through our overuse of antibiotics in humans and animals. There lies the problem. Over-prescribing antibiotics for conditions like the flu or a common cold (against which antibiotics are useless) contributes to antibiotic resistance. What is less well known is that antibiotics are also fed unnecessarily to livestock, poultry, and fish to promote faster growth and to compensate for the unsanitary conditions on factory farms.

Antibiotics and the Animal Industry

Modern industrial livestock operations are an example of how rampant overuse of antibiotics threatens to increase the prevalence of antibiotic-resistant bacteria. These industrial farms have been mixing antibiotics into livestock feed since 1946, when various studies showed that low levels of antibiotics (too low to actually fight disease) seemed to help animals grow faster and put on weight more efficiently, thus increasing profits for meat producers. When antibiotics are used for these purposes – i.e., for purposes other than treating an illness – it is known as non-therapeutic use.

Aside from promoting growth, the routine use of antibiotics is also necessary for preventing disease in conventional industrial farming systems. Modern industrial farms, or confined animal feeding operations (CAFOs), are ideal breeding grounds for germs and disease. Animals live in close confinement, often standing or laying in their own filth, and are under constant stress, which inhibits their immune systems and makes them more prone to infection. Because of these less than hygienic conditions, about half of the antibiotics used by farms are mixed into the feed of healthy animals in order to prevent disease. The trend seems to be to prevent diseased animals by using antibiotics meant for cure, even before any proof of illness, and save on sanitizing the area. Unfortunately, low-level use of antibiotics for extended periods of time is one of the best ways to speed the development of antibiotic-resistant bacteria.

The Union of Concerned Scientists (UCS) estimates that the quantities of antimicrobials administered to livestock and poultry far outweigh the amount of antibiotics used on humans. According to UCS estimates, humans use approximately 4.5 million pounds of antibiotics annually for medical treatment and in topical creams, soaps, and disinfectants. In comparison, antibiotic use in beef, pork, and poultry production is estimated at 24.6 million pounds annually – approximately five and a half times the amount used in human medicine. Thus, the use of antibiotics in livestock agriculture accounts for 84% of total antimicrobial use in America.

Many of the antibiotics routinely given to healthy livestock and poultry to promote growth are identical, or nearly so, to drugs that health providers rely on to treat sick humans. These include penicillin, tetracyclines, erythromycins and bacitracin, among others. For example, the Union of Concerned Scientists estimates that nearly 5 million pounds of two tetracycline antibiotics are fed to swine each year in the U.S. The volume of these two medicines fed to pigs alone, according to UCS estimates, is sixty percent greater than the volume of all antibiotics given to sick humans.

The same mechanisms by which bacteria in humans develop resistance also work in animals that are fed antibiotics. The genes that confer antibiotic resistance to bacteria can travel from food animals to humans via several routes, including on contaminated food and through contamination of the environment.

Contamination of the Environment: Spread of Antibiotic-Resistant Bacteria

Large livestock operations produce an enormous amount of waste – over 1 billion tons annually – that often contains intact and undigested antibiotics, as well as antibiotic-resistant fecal coliforms (bacteria that live in the intestines). It is estimated that as much as 80-90% of all antibiotics given to humans and animals are not fully digested or broken down and eventually pass through the body and enter the environment intact through waste. Thus, these antibiotics are released into the environment where they may encounter new bacteria and create more resistant strains. Many of the antibiotics used on livestock and poultry farms are identical or similar to those used in human medicine, meaning that bacteria from farms can infect people with diseases that can not be treated with common antibiotics.

Antibiotic Resistance and Public Health

The rise of antibiotic-resistant bacteria is a major public health crisis because infections from resistant bacteria are becoming increasingly difficult and expensive to treat. Already, an estimated 14,000 Americans die every year from drug-resistant infections, and the National Academy of Sciences calculates that the increased health care costs associated with antibiotic-resistant bacteria exceed at least $4 billion annually – a figure that reflects the cost of additional antibiotics and longer hospital stays, but not lost workdays or human suffering.

Although everyone will be at risk if antibiotics stop working, the threat is greatest for those with weaker immune systems, such as cancer patients undergoing chemotherapy and organ transplant patients. Young children and seniors are also at particular risk because the immune system functions less effectively for people in these age groups.

Should a colony of drug-resistant bacteria bloom at an industrial livestock operation, there are three basic means by which the germs can make their way to the human population: via food, via the environment (i.e. water, soil, and air), and via direct contact with animals (i.e., farmers and farm workers). It is estimated that 25-75% of all antibiotics administered to animals could be passed unchanged directly into the environment through manure. Since huge quantities of livestock manure are sprayed on farm fields to be re-absorbed into the environment, antibiotic resistant bacteria can leech into ground water and drinking wells, endangering the health of people living close to large livestock facilities.

Alternatives to Antibiotics Available

On industrial farms, animals are administered antibiotics on a routine basis – through feed, water, or injection. But not all animals are raised in such a manner. Ending or minimizing the use of antibiotics in animal agriculture is both feasible and potentially beneficial to consumers. According to a study by the National Academy of Sciences, if the U.S. were to ban the non-therapeutic administration of antibiotics to livestock, the average consumer's total food costs would only increase by $4.85 to $9.72 per year. The study suggested that this ban would not affect the profits of farmers who utilize good management practices. Furthermore, the ban would be expected to decrease health care costs.

In 1997, 14 percent of the U.S. domestic chickens sampled were found to contain Campylobacter bacteria resistant to fluoroquinolone antibiotics. In 2000, the American Public Health Association issued an interim policy calling on manufacturers to withdraw their fluoroquinolone products used in poultry, saying that it "constitutes the quickest, most responsible way to address the public health threat."

In June 2001 the American Medical Association went on record opposing the use of antibiotics in healthy food animals. Other groups of health professionals have taken a similar stand.

Europe is moving in the direction of a total ban on routine use of antibiotics in animal feeds. Sweden and Denmark have already completed a phase-out, while other European Union countries have ended such uses of most antibiotics and are scheduled to end use of the rest by 2006. These nations have led the development of large-scale livestock management techniques that use better hygiene rather than antibiotics to raise healthy animals, with no interruption in the meat supply. A growing roster of U.S. producers also avoids routine use of antibiotics.

Many small, sustainable producers do not use antibiotics at all, in large part because they don’t have to compensate for unhealthy conditions. On sustainable farms, animals are raised in a clean, natural environment that is not a breeding ground for bacteria. Other sustainable farmers will use antibiotics to treat animals only when they become sick, and they will make sure the antibiotics have passed out of the animal’s system before using its meat, eggs or milk.

Federally regulated organic standards prevent antibiotics being used in the production of certified organic meats. In the Eat Well Guide, farmers who never administer antibiotics to their animals carry the label “No Antibiotic Use.” Some sustainable producers will use antibiotics to treat animals that fall ill, and in this case, food from those animals cannot be sold as “USDA Certified Organic” or with the label “No Antibiotic Use.” Eat Well Guide producers who only use antibiotics when an animal becomes ill carry the label “No Routine Antibiotic Use.” In these instances, a suitable amount of time must pass after an animal is treated and before its meat, milk or eggs can enter the food supply.

What You Can Do

Some consumers prefer to buy meat from animals that were never given antibiotics; other individuals are not concerned about medically-necessary antibiotic use. The key is to avoid animals that were fed low doses of antibiotics on a regular basis either to promote growth or prevent disease. Not only does this greatly increase the occurrence of antibiotic-resistant bacteria in our environment and food supply, it also indicates that the animals were probably housed in crowded, unhealthy conditions which make them prone to sickness.

  • Buy directly from the farmer. The best way to know how or if antibiotics were used is to ask your farmer. Find a farmer near you using the Eat Well Guide, an online directory of small farms, stores, restaurants, and online catalogs that offer sustainably-raised meat, poultry, dairy, and egg products.
  • Farmers’ markets are popping up all over the U.S. and Canada as their popularity continues to grow. If you can’t make it to the farm, farmers’ markets are a great alternative. Usually the farmer or someone who works on the farm is available and more than happy to answer your questions about antibiotic use and how the animals were raised.
  • Buy local. When you buy locally produced fruits, vegetables and meat products, you support your local economy. Community Supported Agriculture programs, Farmers’ markets and Co-ops are good options for doing this.
  • Advocate for change. Individual consumers can help bring about broader policy change by urging the government and industry to reduce unnecessary antibiotic use in animal agriculture.
  • Don’t take antibiotics unless you have a bacterial infection! Colds and viruses cannot be treated with antibiotics. And all those products containing antibiotics, such as antibacterial soaps, are no better for you than regular soap, so there’s no need to use them.


  • Antibiotic Resistance
  • Sustainable Living
  • Lewis, Ricki. “The Rise of Antibiotic-Resistant Infections,” FDA Consumer Magazine, September 1995
  • Union of Concerned Scientists, “Hogging it!: Estimates of Antibiotic Abuse in Livestock”. UCS, 2001
  • Union of Concerned Scientists. “Food and Environment, FAQs: Myths and Realities About Antibiotic Resistance.” UCS, June 2003
  • Keep Antibiotics Working. “The Basics: The Health Threat.” KAW, 2003
  • Keep Antibiotics Working, “Antibiotic Overuse in Animals.” KAW, 2003
  • Horrigan, Leo, et al., "How Sustainable Agriculture Can Address the Environmental and Human Health Harms of Industrial Agriculture." Environmental Health Perspectives, Volume 110, Number 5, May 2002.

See Also