Study: Drug-Resistant Bacteria in U.S. Meat

April 15, 2011 -- There’s a new reason to be careful when handling raw meat at mealtimes.

Researchers testing raw turkey, pork, beef, and chicken purchased at grocery stores in five different cities across the U.S. say that roughly one in four of those samples tested positive for a multidrug antibiotic-resistant “superbug” bacterium.

“The findings were pretty shocking,” says study researcher Lance B. Price, PhD, director of the Center of Food Microbiology and Environmental Health at the Translational Genomics Research Institute in Flagstaff, Ariz.  “We found that 47% of the samples were contaminated with Staph aureus, and more than half of those strains were multidrug resistant, or resistant to three or more antibiotics.”

The presence of drug-resistant staph bacteria, a category that includes methicillin-resistant Staphylococccus aureus (MRSA), in farm animals and food has been a closely watched problem in Europe, where it has been traced to outbreaks of human disease.

But less has been known about its prevalence in the U.S. food supply.

“We haven’t looked at this before in the United States,” says Price. “What we don’t know is whether people can pick it up through meat. This is the first time that we’ve even recognized that it’s there.”

“We don’t know where these are coming from, and it’s really something that we have to understand,” he says.

Meat Producers Respond

Food producers say their products are safe.

“Staphylococcus aureus is a very common bacteria found in the environment, and is one of the most common found on human hands. It rarely causes any health problems,” says Hilary Thesmar, PhD, RD, director of scientific and regulatory affairs for the National Turkey Federation in Washington, D.C., in a statement.

“Contamination by human hands is a likely source of contamination of the products in this study,” Thesmar says. “The most important message for consumers is to follow proper food safety methods, such as washing your hands and cooking meat and poultry thoroughly. Following good food safety practices will ensure that consumers continue to enjoy safe, high-quality, and nutritious turkey products.”

Others agree with that assessment.

“Staph aureus is common in everything. It’s common in people. Something like 30% of people carry it in their nasal passages, and it’s on your skin. Finding that in food products wouldn’t have been anything out of the usual,” says Dave Warner, director of communications for the Pork Producers Council in Washington, D.C.

What the Study Found

For the study, researchers collected 136 meat and poultry samples from 26 grocery stores in five cities: Chicago; Washington, D.C.; Fort Lauderdale, Fla.; Los Angeles; and Flagstaff, Ariz.

DNA testing confirmed the presence and specific types of S. aureus bacteria. The bacteria were exposed to antibiotics from different classes to determine which drugs could kill the germs and which could not.