Clustered Gram-negative Salmonella Typhimurium bacteria, the type linked to a salmonella outbreak that resulted in the recall of more than 1,500 foods, are shown under a magnification of 5000X in a colorized scanning photomicrograph. (AP Photo/Centers for Disease Control and Prevention, Janice Haney Carr) ** FILE **

Photo by: Janice Haney Carr

Clustered Gram-negative Salmonella Typhimurium bacteria, the type linked to a salmonella outbreak that resulted in the recall of more than 1,500 foods, are shown under a magnification of 5000X in a colorized scanning photomicrograph. (AP Photo/Centers for Disease Control and Prevention, Janice Haney Carr) ** FILE **