But consumers are being told to throw away many items containing the possibly tainted legume.
Officials believe the Salmonella-containing peanut butter and paste derived from a King Nut plant in Georgia.
According to reports, the plant was operating with unsanitary conditions that include mold and roaches.
King Nut creamy peanut butter is distributed in many states to long-term care facilities, hospitals, schools, universities, restaurants, delis, cafeterias and bakeries. The company’s peanut butter is not sold directly to consumers.
But both Austin and Keebler brands of peanut butter crackers, produced in North Carolina, are also under suspicion.
An association between illness and consumption has been linked with Austin and Keebler brand peanut butter crackers, produced by the Kellogg Company using peanut paste from the Peanut Corporation of America, which also owns King Nut.
More than 180 peanut butter-containing products produced by a variety of companies may have been made with the ingredients produced by the Peanut Corporation of America.
Workers at local grocery stores say they have only had to pull a few items off shelves.
The FDA and product manufacturers are working to define a list of affected products, which may be extensive. Many companies have already announced whether their products include ingredients being recalled by Peanut Corporation of America, and more are expected to make similar announcements.
As of Sunday evening, 501 persons in 43 states had been infected with the outbreak strain of Salmonella Typhimurium.
The illnesses began cropping up between Sept. 1 and Jan. 9, and patients range in age less than 1 to 98 years. Among persons with available information, 22 percent reported being hospitalized. Infection from the tainted peanuts may have contributed to eight deaths.