Tomatoes vulnerability to contamination by salmonella is being studied by scientists at the US Food and Drug Administration (FDA).
From 1973 to 2010, there were 15 multistate outbreaks of illnesses attributed to Salmonella contamination of raw tomatoes, with 12 of these outbreaks taking place since 2000.
They resulted in almost 2,000 confirmed illnesses and three deaths, with states in the eastern US hardest hit, said the agency.
The researchers have collected more than a thousand bacteria in the soil and water in search of a natural enemy of Salmonella and they found a bacterium called Paenibacillus, which is benign to humans but kills Salmonella.
FDA will work with the Environmental Protection Agency (EPA) to facilitate the development of an organic treatment containing Paenibacillus that would kill Salmonella and other harmful organisms.
"The conditions in which tomatoes thrive are also the conditions in which Salmonella thrive," said Eric Brown, Ph.D., director of FDA's Division of Microbiology.
"But the tomato always presented an extra challenge because it is so short-lived. By the time it looked like contaminated tomatoes could be causing illnesses, the harvest would be gone."
The researchers, dubbed “Team Tomato”, are trying to reduce contamination in the beginning.
FDA microbiologist Rebecca Bell, Ph.D., lead researcher on the team, said the agency studies tomatoes on an experimental farm at Virginia Tech's Agriculture and Research Extension Center (AREC) which is next to farms that have been the source of Salmonella contamination.
"There are still a lot of unknowns when it comes to contamination of tomatoes.But our research helps open a window," said Michael Mahovic, Ph.D., a consumer safety officer on FDA's Produce Safety Staff.
The team is also researching the genes of the disease-causing bacteria to prevent illnesses once Salmonella is detected.
FDA wants faster ways to track down the source of an outbreak of foodborne illnesses, explains Captain Thomas Hill, MPH, US Public Health Service, an environmental health specialist in FDA's Coordinated Outbreak Response Network and a member of Team Tomato.
Bell explained that the agency has been developing bacterial genetic sequences (the ordered chemical building blocks of DNA).
It will form part of a public database of bacterial gene sequences allowing scientists to rapidly identify disease-causing bacteria and locate their source.
"Team Tomato is one of the best examples of regulatory science that we have to offer," said Brown.
"The scientific information that Team Tomato has gleaned so far is helping to answer some very tough questions related to tomato safety and Salmonella in the farm environment."
"Considering the number of people who eat tomatoes, the rate of infection from Salmonella is very low. But it's a very popular food, and we are determined to make that risk as low as possible."