For fecal sample submission, fresh feces is preferable, submitted in a screw-cap vial. If the specimen will be delayed for more than a few hours, the sample may be left at room temperature, refrigerated, or fixed. DO NOT freeze or incubate. For fixation, split the sample into two vials, one containing 5-10% formalin and the other containing PVA (polyvinyl alcohol) fixative. Fixative should be added at a ratio of three parts fixative to one part specimen and thoroughly mixed to ensure adequate fixation. Please indicate the time of collection on the submission form. Specimen containers should have leak-proof, screw-on caps.