Harmful Bacteria Found in Samples of U.S. Pork

Medically Reviewed by Louise Chang, MD on November 28, 2012

Nov. 28, 2012 -- Many pork chops and ground pork products in the U.S. may be tainted with antibiotic-resistant bacteria, including one that the USDA does not look for, a Consumer Reports study shows.

The new report also found traces of a drug that is banned in several countries.

But trade groups representing the pork lobby say the new findings overstate the risks associated with tainted pork, and attest to its safety when prepared properly.

According to the study, 69% of pork chops and ground pork samples tested positive for Yersinia enterocolitica, a bug known to cause infections in about 100,000 Americans a year, especially kids. Other bacteria found in pork samples included enterococcus, staph, salmonella, and listeria. Twenty-three percent had none of the bacteria that was tested for. Some of the bacteria seen in the pork samples were resistant to antibiotics.

In addition, researchers found low levels of the drug ractopamine in about one-fifth of 240 additional pork products. This drug is used to promote lean muscle growth in pigs. It is approved for use in the U.S. and some other countries, but banned elsewhere due to safety concerns. Similar drugs may cause restlessness, anxiety, and a quickened heart rate.

The report will appear in the January 2013 issue of Consumer Reports.

Alarming Findings

“We were a bit surprised by the yersinia,” says Jean Halloran. She is the director of Food Policy Initiatives at Consumers Union, the policy arm of Consumer Reports. “This is not a bacteria that USDA requires companies to test for, so it is not regarded as a problem with pork, but it is a significant cause of food-borne illness and this is a sufficiently serious problem.”

Contamination can happen easily in mere seconds. “If you were just a bit careless in the kitchen and drippings from a pork chop get on your lettuce in the refrigerator, or you forgot to wash the knife between cutting meat and salad greens, you could get sick and it would be harder to treat the infection because of its resistance to antibiotics.”

What’s more, “the safety data in support of the use of the drug ractopamine is not sufficient,” she says. “We need the USDA to act.”

Pork Under Scrutiny

Researchers tested 148 samples of meat from pork chops and 50 from ground pork for the presence of bacteria. The pork samples came from many major store brands. Some carried misleading and unapproved claims such as “no antibiotic growth promotants” and “no antibiotic residues.”

Ground Pork More Contaminated Than Pork Chops

Overall, ground pork was more likely than pork chops to harbor bugs. Similar findings could be expected in sources of raw pork, such as pork loin and pork cheeks, but not cured pork products such as bacon or ham, Halloran says.

Philip M. Tierno Jr., PhD, says the new findings are worrisome. He is director of clinical microbiology at New York University Langone Medical Center in New York City.

“When we test an individual with gastrointestinal symptoms, we look for salmonella and staphylococcus aureus and other pathogens, but we also routinely look for yersinia,” he says. The fact that the USDA doesn’t look for this bacteria in pork is of concern.

Antibiotic use in animals is one of the key drivers of antibiotic resistance, Tierno says. “In the U.S., we use antibiotics to prevent, not treat, infections in animals because of how the animals are raised in crowded conditions.”

Safe Pork Guidelines

What can people who eat pork do?

Lots, experts say.

  • Use separate cutting boards for meat and produce. "Throw the cutting board or knife in the sink after you use it,” Halloran says.
  • Choose antibiotic-free pork products, including those labeled “certified organic.” Also look for animal welfare labels such as Animal Welfare Approved or Certified Humane, which prohibit the use of ractopamine and allow antibiotics only for disease treatment, not prevention.
  • Disinfect all objects that come into contact with pork. "A little bleach in water is the cheapest and most effective killer of these germs,” Tierno says. “Combine a whiskey glass of bleach and half a quart of water to disinfect utensils and countertops."
  • Wash hands thoroughly after preparing raw meat.
  • Cook pork thoroughly. Use a meat thermometer when cooking pork to ensure it reaches at least 145 F for whole pork and 160 F for ground pork, Halloran says.

Donald W. Schaffner, PhD, says everyone can eat pork products safely as long as they take the proper precautions. He is a professor of food sciences at Rutgers University in New Brunswick, N.J. “If you like it, you should keep eating it, just cook it thoroughly,” he says. “Not everyone can afford organic meats.”

Pork Industry Responds

Many in the pork industry dispute the findings.

In a written statement, R.C. Hunt, a pork producer from Wilson, N.C., and president of the National Pork Producers Council, says the amount of samples used in the study was way too small to draw any meaningful conclusions. He also says that the new report failed to break the yersinia down by subtypes, only a few of which cause illness in people.

As far as antibiotics in the livestock, “the simple fact is that pork producers like me use FDA-approved antibiotics very judiciously to keep our animals healthy and to produce safe pork for consumers,” he says.

The National Pork Board also takes issue: "Pork is safe. Only a few strains of yersiniacause illness in humans."

The group states that the antibiotic practices used are safe. “The FDA approves antibiotics for use in food animals, which may be used to treat illness and prevent disease, or allow pigs to grow better on less feed, resulting in less waste,” they say in a prepared statement. “Antibiotics used in pork production have many built-in safeguards throughout the food chain to provide safe food.”

Show Sources


Jean Halloran, Director, Food Policy Initiatives, Consumers Union, Yonkers, N.Y.

Donald W. Schaffner, PhD, professor of food sciences, Rutgers University, New Brunswick, N.J.

Philip M. Tierno Jr., PhD, director, clinical microbiology, New York University Langone Medical Center, New York City.

National Pork Producers Council statement.

National Pork Board statement.

Consumer Reports, January 2013.

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