A recent test on ground beef revealed 18 percent of the beef samples from conventionally raised cows contained bacteria resistant to three or more classes of human antibiotics, compared to 9 percent of samples from sustainable beef.

The new article, “How Safe is Your Beef?” published in the October issue of Consumer Reports, investigates more than 300 packages of conventionally and sustainably produced ground beef purchased from grocery, big-box and natural food stores in 26 cities across the country. The samples were tested for five common types of bacteria associated with beef—Clostridium perfringens, E. coli (including O157 and six other toxin-producing strains), Enterococcus, Salmonella and Staphylococcus aureus.

Researchers found bacteria on all the purchased beef samples. However, Consumer Reports says ground beef from cows raised more sustainably was significantly less likely to have two potentially harmful bacteria (S. aureus and E.coli) than that from cows raised conventionally.

“Better ways of producing beef from farm to fork have a real impact on the health and safety of our food and the animals themselves,” says Urvashi Rangan, executive director of the Center for Food Safety and Sustainability at Consumer Reports. “Farming animals without antibiotics is the first step toward a more sustainable system. Grass-fed animals and good welfare practices produce fewer public health risks.”

After a review of the findings, the North American Meat Institute (NAMI) did not dispute the results, but presented them as evidence of how safe ground beef really is. NAMI said the bacteria identified in the report are types that rarely cause foodborne illness and are commonly found in the environment.

“The real headline here is the bacteria that Consumer Reports doesn’t report finding in their testing— Shiga toxin-producing E. coli and Salmonella—which are the foodborne bacteria of greatest public health concern in beef,” says Betsy Booren, NAMI vice president of scientific affairs. “Bacteria occur naturally on all raw food products from beef to blueberries, so finding certain types on some foods in a grocery store is not surprising and should not be concerning.”

Other significant findings from the Consumer Reports tests include:

-More than 80 percent of the conventional beef samples contained two types of bacteria.

-Nearly 20 percent of the beef samples contained C. perfringens, which causes almost a million cases of food poisoning annually.

-Ten percent of the beef samples contained a strain of S. aureus bacteria that can produce a toxin that can make people sick—and cannot be destroyed even with proper cooking.

Because of these findings, Consumer Reports is urging FDA and USDA to ban antibiotic use in animals, increase inspections, bolster labeling requirements and expand animal welfare standards.

However, NAMI calls the antibiotic resistance findings “alarmist and misleading.” According to NAMI, antibiotic resistance is common in nature and expected in bacteria. “What is most important to know is whether certain pathogenic bacteria are resistant to certain types of antibiotics, but Consumer Reports has not specified this information in the materials shared with the industry,” NAMI says.

“Just because a bacterium is resistant to one, two or even three antibiotics doesn’t necessarily make it a superbug,” Booren says. “Superbugs are bacteria that are no longer treatable with antibiotics. The important aspect to look at isn’t the resistance itself, but whether that resistance is a public health danger.”

 NAMI says a recent study of more value is the National Antimicrobial Resistance Monitoring System Report, which found that about 80 percent of human Salmonella isolates are not resistant to any of the tested antibiotics. The report goes on to say resistance to ceftriaxone, azithromycin and quinolones, three important drugs used to treat human Salmonella isolates, remains below 3 percent.