21 CFR §112.144

1. (a)You must test the growing, harvesting, packing, and holding environment for Listeria species or L. monocytogenes in accordance with the requirements of § 112.145.
2. (b)You must either:
   1. (1)Test spent sprout irrigation water from each production batch of sprouts for E. coli O157:H7, Salmonella species, and any pathogens meeting the criteria in paragraph (c) of this section, in accordance with the requirements of § 112.147; or
   2. (2)If testing spent sprout irrigation water is not practicable (for example, soil-grown sprouts harvested with roots or for hydroponically grown sprouts that use very little water), test each production batch of sprouts at the in-process stage (i.e., while sprouts are still growing) for E. coli O157:H7, Salmonella species, and any pathogens meeting the criteria in paragraph (c) of this section, in accordance with the requirements of § 112.147.
3. (c)In addition to E. coli O157:H7 and Salmonella species, you must conduct tests as provided in paragraph (b) of this section for additional pathogens when the following conditions are met:
   1. (1)Testing for the pathogen is reasonably necessary to minimize the risk of serious adverse health consequences or death from use of, or exposure to, sprouts; and
   2. (2)A scientifically valid test method for the pathogen is available to detect the pathogen in spent sprout irrigation water (or sprouts).