Nearly half of meat and poultry—47 percent—sold at U.S. grocery stores is infected with Staphylococcus aureus bacteria. And more than half of those bacteria are resistant to three classes of antibiotics, according to a new study.
To get these results, researchers collected and analyzed 136 samples—covering 80 brands—of beef, chicken, pork and turkey from 26 retail grocery stores in five U.S. cities: Los Angeles, Chicago, Fort Lauderdale, Flagstaff and Washington, D.C. Through DNA testing, researchers found that the food animals were the major source of contamination.
“The fact that drug-resistant S. aureus was so prevalent, and likely came from the food animals themselves, is troubling, and demands attention to how antibiotics are used in food-animal production today,” said Lance B. Price, PhD, senior author of the study and Director of TGen’s Center for Food Microbiology and Environmental Health, in a release.
Antibiotic use on food animals concerns health officials because this practice is contributing to the rising number of antibiotic-resistant strains of disease in humans. “Scientists have found that the abuse of antibiotics—namely the sub-therapeutic use of antibiotics to prevent illness when there is overcrowding, not the treatment of an infection—has resulted in antibiotic-resistant bacteria,” said Barbara Haumann, senior writer/editor for the Brattleboro, Vt-based Organic Trade Association. “This means that antibiotics for use in treating human illness are becoming less effective, and, in some cases, totally ineffective. This is a serious issue.”
The Cambridge, Mass.-based Union of Concerned Scientists has said that agricultural use accounts for 70 percent of all antibiotics used in the U.S., and this practice “provides resistant bacteria with a direct route into people’s kitchens.” In December 2010, the U.S. Federal Drug Administration estimated that 29 million pounds of antibiotics were sold for livestock use in 2009. In June 2010, the FDA released a policy statement recommending that agricultural uses of antibiotics should be limited to assuring animal health. According to the OTA, conventional meat producers feed animals antibiotics “to compensate for overcrowding and unsanitary conditions” and to promote weight gain and feed efficiency.
The U.S. government routinely surveys retail meat and poultry for four types of drug-resistant bacteria, but S. aureus is not among them, reported the study authors. The types of health problems linked to S. aureus range from mild skin infections to life-threatening diseases, such as pneumonia and blood poisoning, according to the National Institutes of Health.
What to do on the Farm
Some meat advocacy organizations criticized the small sample size and the funding source for the study. The research was supported by The Pew Charitable Trusts as part of The Pew Campaign on Human Health and Industrial Farming, which is working to phase out the overuse of the drugs in food animal production. Also, the Washington, D.C.-based American Meat Institute pointed out that “these bacteria are destroyed through normal cooking procedures,” and, thus, aren’t necessarily a health risk.
“They’re right,” said Charles Benbrook, PhD, chief scientist for the Boulder, Colo.-based The Organic Center. “Adequately cooking meat definitely reduces the risk of contamination.” However, Benbrook noted that if people aren’t careful about cleaning cutting boards or the containers in which they store meat, a high-risk situation can result. “Let’s face it, people are busy and aren’t as careful as they should be,” Benbrook said. “Sometimes juices and blood get around the kitchen. That’s where the risk is. That bacteria can hang around the fridge and get picked up by raw foods.” Or, let’s say you touched raw meat while making a meal and failed to thoroughly clean your hands. If you then prepared your baby’s bottle, the bacteria could infect the child. If this bacteria is resistant to antibiotics, any resulting sickness could be untreatable.
A long-term fix, according to Benbrook, begins on the farm. The first step is to end the creation of new antibiotic-resistant genes on livestock farms. “We know how to do this: Stop using sub-therapeutic antibiotics on farms,” Benbrook said. To ensure that meat has been produced without antibiotics, retailers and consumers can choose products bearing the organic label, according to the OTA. These certified organic operations are federally regulated by the U.S. Department of Agriculture.
The next step is to promote animal health and reduce stress, so the animals’ immune systems can handle bacteria that are a normal part of environment. “Conventional agriculture has gone overboard in maximizing the speed of animal growth,” Benbrook said. “Sure, the animals put on a lot of fat and grow fast, but they’re not healthy, and they’re susceptible to bacteria. Whether conventional or organic, farmers have to place a higher premium on healthy animal development.”
And the last step is to prevent cross-contamination of meat at the slaughterhouse, which can spread antibiotic-resistant bacteria.