TUESDAY, July 1 (HealthDay News) -- With the number of people sickened in the nationwide salmonella outbreak now standing at 869, with 107 hospitalizations, U.S. officials acknowledged Tuesday that they were no closer to identifying the source of the contaminant.

The U.S. Food and Drug Administration also announced it was expanding its investigation to include food items normally served with tomatoes. While tomatoes are still the leading suspected source of the bacterial infections in the two-month-old outbreak, officials said they can't rule out other food items associated with tomatoes. But, they declined to say what those other foods might be.

"It would be irresponsible of us at this point to say where we are expanding the testing," said Dr. David Acheson, the FDA's associate commissioner for food protection. "I'm not prepared to discuss what those items might be."

"The tomato trail is not getting cold, rather other items are getting hotter," he added.

Acheson said the FDA has also activated the Food Emergency Response Network, which could bring to 100 the number of laboratories across the country working to identify the source of the outbreak. The network has been activated before, specifically during the spinach outbreak and the contaminated pet food outbreak in 2007.

Dr. Robert Tauxe, deputy director of foodborne, bacterial and mycotic diseases division at the U.S. Centers for Disease Control and Prevention, also said at the teleconference that his agency was conducting a multi-state investigation focusing on the 179 people who have fallen ill since June 1. He did not explain why the CDC was zeroing in on that group of people.

Meanwhile, the advice to consumers remains the same, Acheson said. Avoid raw red plum, red Roma, round red tomatoes, and products containing these raw tomatoes.

To date, infections have been reported in 36 states and the District of Columbia, making it the largest produce-linked salmonella outbreak in U.S. history. There have been no deaths, officials said.

Also Tuesday, the Bush administration's top health official expressed frustration that the salmonella outbreak hasn't been solved yet. Health and Human Services Secretary Michael Leavitt asked Congress for more money and stronger legal powers for food import safety agencies, the Associated Press reported.

CDC officials first acknowledged on Friday that they were no longer sure that the Salmonella Saintpaul outbreak was due to tomatoes alone, or some other food source.

"Whatever this produce item is that's causing illness is probably still out there making people sick," Dr. Patricia Griffin, chief of the Enteric Diseases Epidemiology Branch at the CDC, told reporters late Friday at a special press teleconference.

Health officials have said all along that the bulk of the tomatoes available at the start of the outbreak in mid-April had come from Mexico and parts of Florida. The FDA had sent teams of investigators to Florida and Mexico last month to inspect farms, packing houses and distribution centers.

One factor complicating the search for the cause of the outbreak is a common food industry practice called "repacking."

"Repacking is a situation in which a supplier or a distributor will repack tomatoes to meet a specific customers' requests," Acheson explained. "So, if a customer is wanting small, ripe tomatoes and the supplier does not have a box of small ripe tomatoes, then they will typically go through multiple boxes and pull out ones that meet customers' specifications and repack them. It's a very, very common practice. We've seen reports that it may be as common as 90 percent of tomatoes get repacked, but we don't have confirmation that the number is that high. Obviously this complicates the trace-back," Acheson said Friday.

He also said that it was possible that tomatoes were contaminated at a packing and distribution center, not a particular farm. That means that produce from states that have been cleared may have gone through packing or distribution houses elsewhere, and become contaminated there.

The food poisoning scare ranks as the largest on record in terms of illnesses linked to tainted produce, the CDC said. "This is so far the biggest outbreak with this number of illnesses confirmed by culture," Griffin noted.

More than 300 of the total cases from the current outbreak have come from Texas. Patient ages range from under 1 year old to 99 years old. Half the victims are women.

Salmonella is a bacteria that can cause bloody diarrhea in humans. Some 40,000 cases of salmonellosis are reported in the United States each year, although the CDC estimates that because milder cases are not diagnosed or reported, the actual number of infections may be 30 or more times greater. Approximately 600 people die each year after being infected.

However, the strain of Salmonella Saintpaul had been previously considered rare. In 2007, according to the CDC, there were only three people infected in the country during April through June.

More information

Visit the CDC for more on the salmonella outbreak.