(Matthew Mead | AP Photo) This Jan. 24, 2012, file photo shows a Caesar salad with romaine lettuce. Food regulators are urging Americans not to eat any romaine lettuce because of a new food poisoning outbreak. The FDA says it's investigating an E. coli outbreak that has sickened over two dozen people in several states. The FDA says it's working with officials in Canada, where officials are also warning against romaine lettuce.