The USDA stepped up its fight against the bacteria after being criticized by Democrats and consumer groups for a series of massive food recalls last year. Listeria monocytogenes, which thrives in a cool, damp place like a refrigerator, can be deadly for the elderly, those with weak immune systems and the unborn babies of pregnant women.

The new USDA rule requires U.S. meat plants that produce ready-to-eat products exposed to the environment after cooking to develop a plan to prevent listeria, then to verify the effectiveness of the plan through testing.

"This rule is tough; it's fair; it's based on science," said Elsa Murano, USDA undersecretary for food safety. "It will require plants to share their testing data."

About 2,500 U.S. meat plants produce ready-to-eat meat products, which do not have to be cooked by consumers.

Listeria is killed when foods are heated to a steaming hot temperature. However, many consumers do not cook ready-to-eat meat products like cold cuts.

Pilgrim's Pride Corp., the nation's third-largest poultry producer, recalled more than 27 million pounds of its ready-to-eat turkey and chicken products last October after inspectors found plant floor drains tested positive for listeria.

Federal health officials linked its poultry to a listeria outbreak that caused eight deaths, three miscarriages and at least 45 illnesses, mainly in the Northeast.