A Seattle microbiologist reports that he found the pathogen Staphylococcus aureus on nearly half, and Campylobacter on more than half, of 100 raw chicken samples collected from area grocery stores.
The contaminated poultry included organic as well as conventionally grown chickens.
Mansour Samadpour, the nationally known food scientist who runs the Institute for Environmental Health (IEH), tested 100 retail chickens at the request of Marler Clark, the food-safety law firm also based in Seattle. Marler Clark is the sponsor of Food Safety News.
Samadpour found S. aureas, or staph, in 42 percent of the samples overall and Campylobacter in 65 percent. The supermarket chicken was contaminated with other pathogens as well: 19 percent of the samples tested positive for Salmonella, one tested positive for Listeria, and 10 percent showed the presence of multidrug-resistant S. aureus (MRSA).
In an unusual finding, one of the chicken samples tested positive for E. coli 026, Shiga-toxin producing E. coli (STEC) bacteria more likely to be a contaminant of beef than poultry.
All the chicken in the IEH survey, which included whole fryers and packages of chicken parts, was collected and tested from March 1 to April 4. The chicken was purchased from Fred Meyer, Safeway, QFC, Whole Foods, Costco, Sam’s Club, Albertsons, Thriftway, PCC Natural Markets and Ken’s Market stores.
Bill Marler of Marler Clark noted that Samadpour’s study affirms the findings of other assessments, including results announced last week by the Translational Genomic Research Institute (TGen).
In that report, funded by the Pew Charitable Trusts and published online by Clinical Infectious Diseases, scientists said they found S. aureus on nearly half of 136 raw meat and poultry samples collected from supermarkets in five U.S. cities.
Last year, a Consumer Reports survey found Campylobacter in 62 percent and Salmonella in 14 percent of retail chicken. Earlier this year an investigation by Canada’s CBC TV found two-thirds of samples collected at major grocery stores in Vancouver, Toronto, and Montreal had bacteria resistant to at least one antibiotic.
“This says that raw chicken in our grocery stores is far less sanitary than we think,” said Marler, adding that poultry processing continues to be problematic, whether or not the chicken is mass-produced on industrial farms.
For example, in the Seattle survey, of the 13 organic chickens tested by the IEH lab, four were positive for Campylobacter, four were positive for Salmonella, and three were positive for staph.
Contamination of meat and poultry, for the most part, occurs during slaughtering, but drug-resistant S. aureus may come from the animals themselves. The TGen researchers implicate the widespread use of antibiotics in industrial agriculture, although the meat industry disputes whether this may be contributing to MRSA.
Last month, the U.S. Department of Agriculture announced stricter standards aimed at reducing Salmonella and Campylobacter contamination of raw broiler chicken and turkey. Under the new rules, which go into effect in July, Salmonella contamination will be allowed in 5 out of every 51 poultry carcasses tested, compared with 12 out of 51 positives under the current standard. A new, first-ever standard for Campylobacter will be no more than 10.4 percent positive samples for chicken.
Salmonella causes approximately 1.4 million illnesses and 400 deaths and Campylobacter is responsible for more than 800,000 illnesses and 76 deaths in the U.S. annually. Staph is the cause of some 240,000 foodborne illnesses a year, according to Centers for Disease Control and Prevention estimates. The CDC notes that staph is a common bacterium found on the skin and in the noses of up to 25 percent of healthy people and animals.
Marler says the government’s new standards for testing poultry are a step forward, but in his opinion are still too high for allowable contamination. “We need to move toward zero tolerance for pathogens,” he said, adding that there is no screening for Staphylococcus aureus.
But Marler doubts whether additional testing or regulatory action can actually do much more to ensure that chicken is safe.
“I see it less as a regulatory response than a response needed from chicken growers and consumers,” he explained. “Chicken growers should continue to strive for bacteria reductions – especially in pathogens like E. coli and antibiotic-resistant Campylobacter, Staph and Salmonella.
“And consumers need to be more vigilant and also buy from chicken growers who have the lowest bacterial counts.”
Cooking poultry to an internal temperature of 165 degrees, as measured with a tip-sensitive digital thermometer, can help keep it safe. Staph-contaminated meat may be more risky, however. As the germ grows in food it produces toxins that are resistant to heat, although some experts say there would have to be significant growth of toxic organisms for this to be a concern.
Cross contamination is another problem. Raw poultry can contaminate shopping carts, checkout counter conveyor belts, kitchen cutting boards and utensils, and food handlers can contaminate uncooked foods such as salads if they don’t wash their hands and take other precautions when working with raw poultry.
Marler said one result of the Seattle chicken tests that startled him was the discovery of E. coli O26.
He said he could only speculate about how raw chicken could become contaminated with E. coli O26 but “to my mind, it is a very large worry.”
In 2008, Marler commissioned the Institue for Environmental Health to sample 5,000 packages of ground beef for all strains of E. coli. In that survey, Samadpour found that about 2 percent of the meat was contaminated by non-O157 strains of E. coli. Marler Clark then petitioned the USDA to declare these Shiga-toxin E. coli bacteria as adulterants.