In this task, you are given a sentence. You are expected to write the name of the organism substances in the body mentioned in the input. Although there might be several correct answers, you need to write one of them.
Example: Antisperm antibodies were assessed in the serum samples of 73 men unable to ejaculate naturally and on the sperm cells of 13 of these men.
Example solution: serum
Example explanation: Serum is a substance of the organism and needs to be tagged.

Problem:  Data from this study suggest that there may be a time - dependent relationship between dexamethasone immunosuppression and the fecal concentration of E . coli O157 but that transient immunosuppression does not appear to prolong shedding of E . coli O157 .

Solution: fecal