Has anyone read or heard of new CDC recommendations about doing weekly bacteria cultures of water systems? Or, has anyone heard of any changes to the AAMI recommendations? As far as I know, the recommendation is monthly.

I haven't heard of anything but our MD requests that we do cultures every other week on our water system and monthly on the dialysis machines.

I just pulled the new CDC guidelines down from this web page. Looks like monthly sampling is specified. The use of the phrase "at least monthly" would indicate more is better though and the guideline does a great job of outlining the pertinent issues. Read it carefully.