A new study of meat and poultry sold in grocery stores by the Translational Genomics Research Institute (TGen) found that 47 percent of samples tested were contaminated with Staphylococcus aureus and 52 percent of those contained strains that were resistant to at least three classes of antibiotics.
The study analyzed 136 samples of beef, chicken, pork and turkey from 26 grocery stores located in Chicago, Flagstaff, Fort Lauderdale, Los Angeles and Washington, D.C.
Researchers suggested that food animals given high doses of antibiotics were the major source of contamination.
"The emergence of antibiotic-resistant bacteria -- including Staph -- remains a major challenge in clinical medicine," Paul Keim, Ph.D., director of TGen's Pathogen Genomics division and director of the Center for Microbial Genetics and Genomics at Northern Arizona University (NAU), said in a press release.
"This study shows that much of our meat and poultry is contaminated with multidrug-resistant Staph. Now we need to determine what this means in terms of risk to the consumer," said Dr. Keim.
"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," said Lance Price, Ph.D., senior author of the study and director of TGen's Center for Food Microbiology and Environmental Health.
The meat industry was quick to take issue with TGen's methodology and findings.
According to an American Meat Institute (AMI) press release, "Federal data from the Centers for Disease Control and Prevention (CDC) show steady declines in foodborne illnesses linked to consumption of meat and poultry overall and indicate that human infections with Staphylococcus aureus comprise less than one percent of total foodborne illnesses."
The AMI pointed to a white paper by Ellin Doyle of the University of Wisconsin's Food Research Institute, which found Staph bacteria are found in half of all human nasal passages. Dr. Doyle's white paper noted that in the only two foodborne outbreaks of antibiotic resistant Staph, food handlers and not the food source were to blame for the spread.
Interestingly, the TGen research supports this last position noting that Staph is usually killed with proper cooking. According to the authors, "it may still pose a risk to consumers through improper food handling and cross-contamination in the kitchen."