I don't think that I am alone in my struggle to comply with the new RD52 guidance of an action limit of 50 cfu for delivery systems. Until recently I held as a truth that strict compliance with the manufacturer's guidance for machine disinfection, along with a clean water system, would keep my delivery systems in compliance. This is no longer appears to be true. My question to the group:
Fresenius uses the term "disinfection" quite liberally in the operators manual for the H and K machine and I have seen no true definition of the term (in the manner of the FDA). What is your microbiological expectation of a deliver system post disinfection cycle?

Disinfection according to AAMI RD52.

Destruction of pathogenic and other kinds of microorganisms by thermal or chemical means. Disinfection is a less lethal process than sterilization, because it destroys most recognized pathogenic microorganisms but does not necessarily destroy all microbial forms. This definition of "disinfection" is equivalent to low-level disinfection in the Spalding classification.

I would be concerned about your cultures. My machines have DiaSafe filters and are almost always no growth. However, I will sometimes have bacterial growth near the action level in the loop just before scheduled storage tank and loop disinfection with 1% bleach.

You need to be able to demonstrate that your disinfection procedures and schedule enables you to produce water that meets standards. Is it only your machines that have the problem? We disinfect from the storage tank, into the loop and through the machines monthly.

I hope I was of some help.

Thanks - all information and opinion is useful.

See - " Regulatory Status of Disinfectants Used to process Dialysate Delivery Systems and Water Purification Systems for Hemodialysis; Guidance for Industry and FDA ". August 30, 2002. Yes, that's the whole title. Go to -www.fda.gov/cdrh/ode/guidance/1419.pdf or to recieve docment by fax call 1-800-899-0381, after voice prompt enter docment ( 1419 ).