This 2009 electron microscope image provided by the Centers for Disease Control and Prevention shows a large group of Gram-negative Salmonella typhimurium bacteria that had been isolated from a pure culture. Poultry producers will be required to bring salmonella bacteria in certain chicken products to very low levels to help prevent food poisoning under a final rule issued Friday, April 26, 2024, by the U.S. Department of Agriculture. (Janice Haney Carr/CDC via AP)