Consumer Reports tested 458 pounds (or the equivalent of 1,832 quarter-pounders) from 103 grocery, big-box and natural-food stores in 26 cities across the country. They analyzed the samples from five common types of bacteria found on beef: Clostridium perfringens, E. coli (including the deadly O157 and six other toxin-producing strains), enterococcus, salmonella and Staphylococcus aureus.
Their results may make you rethink that hamburger.
All 458 pounds of beef contained at least one of the types of bacteria. Ten percent of the samples were contaminated with a strain of S. aureus that, under certain circumstances, can produce a toxin that can make you sick -- and that can't be destroyed with proper cooking.
However, other experts say it would be difficult for these conditions to exist in the average consumer's kitchen.
The meat industry said the findings actually show the overall safety of beef. Testers did not find the deadly strain of E. coli O157, according to a statement from the North American Meat Institute.
The U.S. Department of Agriculture says it has implemented tighter food safety standards than ever before on ground beef and the overall meat industry. They include measures that include a zero-tolerance policy for six dangerous strains of E. coli and better procedures for detecting the source of outbreaks.
One of the most significant findings, said Urvashi Rangan, executive director of the Center for Food Safety and Sustainability at Consumer Reports, is that beef from conventionally raised cows was more likely to have bacteria overall, as well as bacteria that are resistant to antibiotics, than beef from sustainably raised cows.
Sustainable methods range from the basic, such as beef raised without antibiotics, to the most sustainable, which is grass-fed organic. Grass-fed cattle usually don't get antibiotics and spend their lives on pasture, not feedlots, according to Consumer Reports.
In the past, when the group tested for bacteria in shrimp, ground turkey and chicken, testers weren't able to obtain large samples of sustainably raised products, Rangan said. Nor did testers find a big difference in the prevalence of bacteria between conventional and sustainable meat-production methods.
But this time, Consumer Reports found that of the conventional beef samples, 18 percent were contaminated with superbugs — dangerous bacteria that are resistant to three or more classes of antibiotics — compared with 9 percent of beef from samples that were sustainably produced.
But what about the cost?
Rangan agreed that it costs more to buy sustainably raised beef. But she suggested that consumers could reduce their red meat consumption and save their dollars to buy better beef. Buying directly from farmers who raise their cows this way, or from farmers markets, is another possibility, she said. In some places, such as New York City, consumers can get twice the value for food stamps at farmers markets.
Bottom line: If you cook your meat to 160 degrees, that should kill all the bacteria. Period.