Hello everyone...my first post as I'm new to the forum. Our program's first response to any positive culture results from routine monthly water and dialysate samples is an immediate retest without any interventional disinfection. The rationale, according to my predecessor, was that "false positives " are not uncommon with this type of sampling, for varied reasons. I'm trying to determine if there is any mandate or reccomendation by any regulatory organization ( like AAMI )that specifically adresses retesting as a first course of action. Or is this an action which has evolved as standard acceptable practice over time ? Thank you !

In the AAMI Standards RD62 they state if the action levels are observed in the product water, corrective measures, such as disinfection and retesting, shall be taken promptly to reduce the levels into an acceptable range.

A 'false positive' result can only happen due to a) poor sampling technique, b) contaminated sample container or c) contamination of the sample at the lab.

I would suggest that the action to be taken after any high result is to disinfect and then re-sample. You could, for interest, take a sample immediately before disinfecting for comparison.