A close look at ground beef reveals some pretty disturbing stuff, a Consumer Reports investigation found. Some 300 packages containing 458 pounds of ground beef were bought at stores of all kinds in 26 cities, and every single one contained fecal contamination.

That's more than just gross: It can cause serious illness when beef isn't cooked to the recommended 160 degrees Fahrenheit. Any meat can make you sick if not cooked properly, Consumer Reports notes, but ground beef is especially risky because cows raised on crowded feedlots tend to have manure on their skin, which contains bacteria that can end up in the meat during processing—and bacteria from one cow can end up mixed with that of many other cows.

The testing also revealed antibiotic-resistant "superbugs" in some of the meat, though they were a lot less prevalent in beef labeled "grass-fed organic," which tended to have less bacteria overall.

Experts advise consumers to buy sustainably raised beef when they can—and always make sure it's cooked all the way through. "Remember, when it's ground beef, you're taking it and grinding the bacteria from the surface of the beef into it," Consumer Reports' director for food safety tells CBS.

"So unlike a steak, you're really moving all that bacteria all around the beef. So it's especially important for ground beef, to cook it to 160 degrees to be absolutely safe." (Health officials say "cannibal sandwiches" are a very bad idea.)

This article originally appeared on Newser: Almost All Ground Beef Has Fecal Contamination

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