This guidance provides information about designing pathogen testing kits so that they will be appropriate for their intended use, perform comparably to the FSIS method (if applicable), and not have introduced modifications that could compromise test performance. It applies to test kit developers, laboratories, and independent validation organizations who design test kits or test for Escherichia coli O157:H7 or non-O157 Shiga toxin producing E. coli (nonO157 STEC). Establishments may use such pathogen test kits to ensure compliance with the requirements of 9 CFR 417.