The department suspended the raw processed meat operations of Topps after an initial recall of 331,582 pounds of frozen ground beef products.
"This is frozen product" and could still be in home freezers, said Richard Raymond, the Agriculture Department's undersecretary for food safety. He added that "consumers have a big role" in getting the meat out of circulation.
Products affected by this expanded recall were distributed to retail grocery stores and food service institutions throughout the United States including Pathmark Stores and Wal-Mart Stores.
Based on consumption patterns, Topps said it believes that the vast majority of the recalled product has been consumed.
Raymond said USDA sent a food safety assessment team to Topps and found it did not follow proper meat handling procedures. The company, which is the largest US producer of frozen hamburger patties, kept meat from one day's operations and then mixed it into the next day's run, Raymond said.
USDA is trying to find the source of the bacteria. For now, a spokeswoman with USDA's Food Safety and Inspection Service said the agency's "biggest interest is getting the word out to consumers."
E. coli O157:H7 can cause diarrhea and dehydration. Children, the elderly and people with poor immune systems are the most susceptible.
The Consumer Federation of America said in a statement that the Topps recall shows "a major revision of food safety laws" is needed to protect consumers.