Bloomberg reports that a Kellogg cookie plant in Augusta, Georgia, was found to have a persistent strain of listeria during a February inspection, including on food-contact surfaces, according to a warning letter from U.S. regulators. The Food and Drug Administration letter, dated June 7, was sent less than two years after a Kellogg Eggo waffle plant in the same state was shut for similar reasons. The inspection found flies and pools of water, the FDA said. The letter from District Director John Gridley didn’t say that any products were tainted with listeria, yet said they were adulterated and may have become contaminated with filth. The Augusta plant makes Keebler and Famous Amos cookies, and is one of five cookie bakeries Kellogg operates in North America. The regulator gave Kellogg 15 days to outline specific remedies to avoid injunction or product seizure.