MIMIC-IV 1.0 C. diff. test encoding

[tchang1997]

I am currently trying to extract information about whether a patient was tested for C. diff. within an admission, as well as the test result(s). However, I ran into some issues, and I want to make sure that my encoding procedure is correct.

1. There are C. diff. tests and results in both hosp/labevents.csv and hosp/microbiologyevents.csv. The hosp/microbiologyevents.csv table has much more results; the patients/admission IDs in the two tables don't necessarily overlap. Are both tables supposed to be aggregated as a source of test results?
2. A small set of patients (~400-500) have multiple lab tests within the same admission (identical subject_id and hadm_id) that do not concord. I'm even seeing a few cases of the same reported test_id yielding different results for the same subject_id, hadm_id pair (I'd show examples, but I don't know that showing specific IDs is allowed). I've seen "rules" for handling these (i.e. using PCR/DNA amplification as a "tiebreaker" test when C. diff. toxin and antigen tests contradict), but is there a "rule" for MIMIC to handle cases with multiple tests?

Thanks so much in advance!