United States-Salmonella in peanut butter.

UNITED STATES-SALMONELLA.

The maker of peanut butter linked to a nationwide outbreak of salmonella shipped tainted product it knew had tested positive for the bacteria, the Food and Drug Administration said Wednesday.

The FDA report said the Peanut Corporation of America’s own testing program found strains of salmonella 12 times in 2007 and 2008 at its Blakely, Georgia, plant. The problem does not appear to have been resolved. When FDA inspectors visited the plant this month, they reported finding still more salmonella contamination.

According to the inspection report, posted at FDA’s Web site, the "firm’s own internal microbiological testing" found salmonella in peanut paste, peanut butter, peanut meal, peanut granules and oil-roasted, salted peanuts.

In each instance, peanut products tested positive for salmonella contamination, the report said.

However, it added, "After the firm retested the product and received a negative status, the product was shipped."

That’s not the way it ought to have been handled, according to one expert. "They were lab shopping," said Tommy Irwin, Georgia’s agriculture commissioner. "They were trying to find a way to clear their product, so they can ship their product out," he told CNN.

He said proper practices demand that if any food product tests positive for salmonella and another test comes back negative, "you believe the one that is positive."

Once salmonella is found in a product, "that lot should be destroyed, but [in this case it] wasn’t," Irvin said.

The Georgia Department of Agriculture is working with the FDA on the investigation of the outbreak, which has been linked to the plant.

"The inspection also revealed no steps were taken in terms of cleaning or cross-contamination" after the salmonella was found in the plant, said FDA’s director of the Center for Food Safety and Applied Nutrition, Dr. Stephen Sundlof.

The company did not clean the production line after Salmonella Typhimurium, the bacterium implicated in the outbreak, was found there last September, according to the FDA report. This is the same type of bacteria found in 502 people who have become ill in 43 states and Canada since September. At least eight deaths have been linked to the outbreak.

Violations also include contamination of plant surfaces and equipment by other microorganisms, the discovery of roaches near production and packaging areas and the inability of the company’s ventilation system to prevent the salmonella from contaminating other parts of the plant.

Sundlof said the reported problems indicate the plant deviated from the good manufacturing practices companies are supposed to follow.

A Peanut Corporation of America spokesman said Wednesday afternoon in an e-mail that the company had no comment but might issue a statement after a later briefing by the FDA.

On Tuesday, in a written statement, the company said it "has cooperated fully with FDA from Day One during the course of this investigation. We have shared with them every record that they have asked for that is in our possession and we will continue to do so."

The FDA investigation began January 9, shortly after the manufacturer was implicated as a source of the outbreak. The plant produces peanut butter sold to institutions, such as nursing homes and cafeterias, as well as peanut paste, which is used in cookies, crackers, ice cream and pet treats.

This month, PCA began recalling peanut butter and paste produced since last July 1. However, the recall has not been expanded to include products produced before this date, even though Wednesday’s report indicates the company found salmonella in its plant as long ago as 2007.

"The recall may increase" and may ultimately become one of the largest in agency history, Sundlof told CNN.

More than 300 products using PCA’s peanut paste and peanut butter have already been recalled and the FDA has urged consumers to check the agency’s Web site frequently for updates. See a list of recalled products.

Federal health officials recommend that consumers throw away any recalled products and not consume any products whose safety cannot be verified.

The American Peanut Council has compiled a list of companies not implicated in the recall on www.peanutsusa.com.