Instructions are also provided for the testing of sprouts for those instances when it is not possible to test spent irrigation water. However, for the reasons discussed below, sprouts should not be tested in lieu of water. The number of cultureconfirmed cases in each outbreak ranged from eight to more than 500, and more than 1,300 cases have been confirmed overall.
Seeds are the likely source of contamination in most outbreaks.
However, current treatments cannot guarantee total elimination of pathogens. If only a few pathogens survive a seed disinfection treatment, they can grow to high levels during sprouting and contaminate the entire batch. Therefore, seed disinfection treatments should be combined with microbial testing to ensure pathogens are not present before sprouts enter the food supply. A production lot or batch is defined as sprouts from a single lot of seed that were started at the same time in a single growing unit, such as a single drum or a rack of trays. Spent irrigation water that has flowed over and through sprouts is a good indicator of the types of microorganisms present in the sprouts themselves.