The latest round of tests by federal scientists, quietly published in February, has documented startlingly high percentages of supermarket meat containing antibiotic-resistant bacteria, according to a new Environmental Working Group analysis.

EWG’s analysis of data buried in the federal government’s National Antimicrobial Resistance Monitoring System has found that store-bought meat tested in 2011 contained antibiotic-resistant bacteria in 81 percent of raw ground turkey, 69 percent of raw pork chops, 55 percent of raw ground beef and 39 percent of raw chicken parts.

“Consumers should be very concerned that antibiotic-resistant bacteria are now common in the meat aisles of most American supermarkets,” said EWG nutritionist Dawn Undurraga, the report’s principal author. “These organisms can cause foodborne illnesses and other infections.  Worse, they spread antibiotic-resistance, which threatens to bring on a post-antibiotic era where important medicines critical to treating people could become ineffective.”

EWG researchers found that 53 percent of raw chicken samples were tainted with an antibiotic-resistant form of Escherichia coli, also known as E. coli, a microbe that normally inhabits feces and can cause diarrhea, urinary tract infections and pneumonia. The extent of antibiotic-resistant E. coli on chicken is alarming because bacteria readily share antibiotic-resistance genes.

As well, EWG found that antibiotic resistance in salmonella is growing fast: of all salmonella microbes found on raw chicken sampled in 2011, 74 percent were antibiotic-resistant, compared to less than 50 percent in 2002.

A significant contributor to the looming superbug crisis is the unnecessary antibiotic usage by factory farms that produce most of the 8.9 billion animals raised for food in the U.S. every year. Industrial livestock producers routinely give healthy animals antibiotics to get them to slaughter faster or prevent infection in crowded, stressful and often unsanitary living conditions.

Pharmaceutical makers have powerful financial incentives to encourage abuse of antibiotics in livestock operations. In 2011, they sold nearly 30 million pounds of antibiotics for use on domestic food-producing animals, up 22 percent over 2005 sales by weight, according to reports complied by the FDA and the Animal Health Institute, an industry group. Today, pharmaceuticals sold for use on food-producing animals amount to nearly 80 percent of the American antibiotics market.

“Slowing the spread of antibiotic resistance will require concerted efforts, not only by the FDA and lawmakers, but by pharmaceutical companies, doctors, veterinarians, livestock producers and big agribusinesses,” said Renee Sharp, EWG’s director of research. “It’s time for big agribusiness to exercise the same restraint shown by good doctors and patients: use antibiotics only by prescription for treatment or control of disease.”