The agency has asked state and local health officials to focus their efforts on items commonly used in the production of fresh salsa, particularly that made in local restaurants, says CDC spokesman Glen Nowak.
Salsas are typically made with tomatoes, onions, jalapeños, garlic and cilantro. They can also include tomatillos and other produce.
The CDC and state health officials are also investigating possible connections between clusters of people who became ill and ate at 29 different restaurants. Most reported eating foods commonly served with tomatoes. The majority of the restaurants featured Mexican food.
The focus does not involve commercially produced salsas, Nowak says. Salsas purchased in cans, jars or plastic containers in the refrigerated section of the supermarket are not being investigated. Fresh-made salsas only, prepared in the home or local restaurants, are the focus.
Tomatoes, originally considered the sole source of the outbreak, remain one of the targeted items, investigators say.
The CDC does not currently have new recommendations for consumers on what to avoid as the investigation is ongoing. The Food and Drug Administration's suggestion to avoid red round, Roma and plum tomatoes grown in certain areas is still in effect. (For more information, go to www.fda.gov.)
The latest figures for the outbreak are 887 sickened nationwide, with an additional 18 newly confirmed cases. At least 108 people were hospitalized.
If the outbreak ends up not being associated with tomatoes, growers will have taken a tremendous hit for nothing, says Tom Nassif, president and chief executive of Western Growers, which represents produce producers in California and Arizona.
If tomatoes are exonerated, Nassif says growers might ask for financial relief from Congress.
Bill Marler, one of the nation's leading food-safety attorneys, says the FDA can't be faulted for acting in the absence of a "smoking tomato" laced with the salmonella bacteria.
"Should they have waited until they knew exactly what it was? Well, whose side do they want to come down on: the side of public health and kids or the produce industry?" Marler asks.