According to a nationwide study by the Translational Genomics Research Institute (TGen), drug-resistant strains of Staphylococcus aureus (S. aureus), a bacteria linked to a wide range of human diseases, are present at high rates in meat and poultry from U.S. grocery stores.
Nearly half of the meat and poultry samples were contaminated with S. aureus, and more than half of those bacteria — 52 percent — were resistant to multiple classes of antibiotics, rendering S. aureus a superbug. S. aureus can cause a range of illnesses from minor skin infections to pneumonia, endocarditis and sepsis.
Researchers claimed this was the first national assessment of antibiotic resistant S. aureus in the U.S. food supply, and that DNA testing suggests the major source of contamination is the very animals that constitute our meat supply.
“For the first time, we know how much of our meat and poultry is contaminated with antibiotic-resistant Staph, and it is substantial,” said Lance B. Price, Ph.D., senior author of the study and Director of TGen’s Center for Food Microbiology and Environmental Health.
The fact that drug-resistant S. aureus was so prevalent, and likely came from the food animals themselves, is troubling, said Price, and demands attention to how antibiotics are used in food-animal production today.
Densely-stocked industrial farms, where food animals are steadily fed low doses of antibiotics, are ideal breeding grounds for drug-resistant bacteria that move from animals to humans, the report says.
“Antibiotics are the most important drugs that we have to treat Staph infections; but when Staph are resistant to three, four, five or even nine different antibiotics — like we saw in this study — that leaves physicians few options,” Dr. Price said.
The study was published in the journal Clinical Infectious Diseases. 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.
The study reinforces what consumer activists have known for years — mass quantities of antibiotics are routinely pumped into animal feed and water.
“Conventional concentrated animal feeding operations (CAFOs) provide all the necessary components for the emergence and proliferation of multidrug-resistant zoonotic pathogens. In the United States, billions of food animals are raised in densely stocked CAFOs, where antibiotics are routinely administered in feed and water for extended periods to healthy animals. NARMS has shown that multidrug-resistant E. coli and Enterococcus species are prevalent among US meat and poultry products. Our findings indicate that multidrug-resistant S. aureus should be added to the list of antimicrobial-resistant pathogens that routinely contaminate our food supply.”
The U.S. government routinely surveys retail meat and poultry for four types of drug-resistant bacteria, but S. aureus is not among them. The paper suggests that a more comprehensive inspection program is needed.
The antibiotic-resistant staph infection known as MRSA — methicillin-resistant Staphylococcus aureus — kills more Americans than AIDS, and is widespread in the U.S. pig herd. The Center for Disease Control reported 94,360 “invasive MRSA infections” in the United States in 2005 — of which 18,650 resulted in death.
In the U.S., 35 million pounds of antibiotics were used in 2009, 70 percent — 28 million pounds — were used on U.S. animals alone. Federal studies routinely discover drug-resistant bacteria in meat sold in our nation’s supermarkets.
The World Health Organization acknowledges the link between resistant bacteria and the regular and unnecessary use of antibiotics in industrial farming, and the Europeans have banned the use of antibiotics in livestock except to treat illness.