Antibiotic Resistance from Animal Agriculture

Antibiotic Resistance from Animal Agriculture: Foodborne Illness and Medical Care

A Report from the Physicians Committee for Responsible Medicine
September 2011

In spring 2011, a massive Escherichia coli outbreak spread across 16 European countries, leading to roughly 3,000 diagnosed cases and many more undiagnosed. The bacterial strain responsible for the outbreak was resistant to several common classes of antibiotics, leaving few treatment options for those affected.

E. coli can cause severe digestive symptoms, including stomach cramps, bloody diarrhea, and vomiting. Some strains can lead to hemolytic uremic syndrome, a type of potentially fatal kidney failure. In the 2011 European outbreak, 852 people developed hemolytic uremic syndrome in Germany alone, and 32 died. Within a month, this deadly strain reached the United States, where it sickened six people and killed one. 

This is not an isolated case. Foodborne infections are common, and many of the implicated bacterial strains show resistance to commonly prescribed antibiotics. About 70 percent of bacterial infections in humans are resistant to at least one antibiotic,² posing serious challenges to treating foodborne infection outbreaks. One-third of victims required hospitalization in spring and summer of 2011, when multidrug resistant Salmonella Heidelberg infections spread to 31 states through ground turkey. At least 111 people were sickened and one killed before the 36 million pounds of contaminated product could be recalled from grocery stores and households in the United States.

The growing public health threat of antibiotic resistance is almost entirely attributed to antimicrobial use in animal agriculture.

Antibiotic Use on Farms

Animals raised for meat and dairy products are routinely treated with antibiotics to promote growth and reduce the risk of illnesses that would otherwise be common in crowded living conditions. Currently, 80 percent of antibiotics used in the United States are administered to animals on farms.

According to a summary report from the U.S. Food and Drug Administration (FDA), more than 50 varieties of antimicrobials belonging to some 20 chemical classes have been approved for use on farms. The most commonly used and aggressively marketed drugs include aminoglycosides, cephalosporins, ionophores, lincosamides, macrolides, penicillins, sulfas, and tetracyclines. The antimicrobials are often added to the feed and drinking water of dairy cows and egg-laying hens, as well as meat-producing chickens, cows, pigs, turkeys, and even fish.

Widespread use of antibiotics can give rise to resistant bacteria, which may or may not cause disease in the animals. Through contact with farm workers and contaminated waste runoff, resistant bacteria can spread to humans and to other animals. Bacteria can also transfer resistance traits to other strains and classes of bacteria.

In June 2010, FDA issued a voluntary guidance to farmers, calling the resistant-bacteria problem a “public health issue of some urgency.”