Posted on December 31, 2012
A product testing organization found Yersinia enterocolitica
in 69 percent of pork samples tested, according to a recent announcement.
The results published by Consumer Reports indicated the organization tested for the presence of certain bacteria in about 200 samples from pork chops and ground pork bought in six U.S. cities. About 11 percent also contained Enterococcus organisms, 7 percent contained Staphylococcus aureus, 4 percent contained Salmonella organisms, and 3 percent contained Listeria monocytogenes.
The announcement and a related article were published online in late November 2012, and the article was scheduled for print publication in January.
The article also noted that 121 of 132 Yersinia isolates tested for drug resistance were resistant to at least one antimicrobial.
Dr. H. Scott Hurd, an associate professor at Iowa State University and former Department of Agriculture deputy undersecretary for food safety, said Y enterocolitica is fairly common in raw pork, but high numbers of the right serotype typically are needed to cause illness in humans. He said concern about the bacteria is low enough that the Department of Agriculture does not test for its presence.
“Yersinia is such a low concern from a public heatlh standpoint that there’s not a lot of information on it,” Dr. Hurd said.
About 98,000 people were sickened by Y enterocolitica annually from 2000-2008, most commonly causing diarrhea and abdominal pain, according to information from the Centers for Disease Control and Prevention. The bacteria are most often spread to humans through contaminated food, particularly undercooked or raw pork.
Yersinia enterocolitica–related illness is most common among children, according to the CDC. Dr. Hurd said smaller amounts of the pathogen can cause illnesses in children, compared with adults.
Cathy Cochran, a spokeswoman for the USDA Food Safety and Inspection Service, said tests used to detect Yersinia bacteria are not very effective at distinguishing between pathogenic and nonpathogenic strains. She said the percentage of samples containing Yersinia bacteria in the Consumer Reports tests suggest the company data include nonpathogenic strains, but the FSIS would need more information on the testing methods to better understand the data.
Cochran noted that two Yersinia outbreaks have been reported since 2005, one each connected with pasteurized milk and raw pork chops. The bacteria are not considered to be an adulterant, which would require removing contaminated items from the food supply.
Officials with Consumer Reports indicated they were willing to respond to requests for additional information but did not respond by press time.
Information provided by the National Pork Board states that, with proper cooking, “Pork is safe.” The organization’s statement also states that federal government research has yet to show resistant bacteria are transferred from animals to humans.
The Consumer Reports article also notes that the organization found traces of ractopamine in about one-fifth of 240 pork samples tested for the drug. The meats with ractopamine residues had fewer than 5 PPB of the drug, one-tenth the limit allowed under federal regulations. But the announcement noted that Consumer Reports’ policy and action arm, Consumers Union, does not think ractopamine use has been proved to be safe and thinks its use should be prohibited.
Dr. Hurd estimated that, based on tolerance levels found through experimental studies, an adult would need to eat about 700 pounds of raw pork daily for years to have noticeable effects from ractopamine residues. He also noted that a compound similar to ractopamine is included in a medication his children take for asthma.