CMS SOM App. H, Tag V178

4.1.2 Bacteriology of water: Product water used to prepare dialysate or concentrates from

powder at a dialysis facility, or to process dialyzers for reuse, shall contain a total viable

microbial count lower than 200 CFU/mL and an endotoxin concentration lower than 2

EU/mL

The action levels for the total viable microbial count in the product water shall be 50

CFU/mL, and for the endotoxin concentration, 1 EU/mL. If those action levels are observed

in the product water, corrective measures shall promptly be taken to reduce the levels.

Interpretive Guidance § 494.40(a)

AAMI Rationale for the Development and Provision of This Recommended Practice

A.4.1.2 Bacteriology of water

When ANSI/AAMI RD5:1981 was initially developed, it was generally considered that the water

used to prepare dialysate did not require sterilization. Studies have demonstrated that the

incidence of pyrogenic reactions is directly related to the number of bacteria in dialysate. It is

also known that a dialysate delivery system can amplify the level of bacteria in the water used to

supply the system. Those studies provided the rationale for setting a recommended maximum

concentration of 200 bacteria per mL in the water used to prepare dialysate.

Several groups of investigators have convincingly demonstrated that pyrogenic reactions are

caused by lipopolysaccharides, also known as endotoxins, associated with Gram-negative

bacteria. Gram-negative water bacteria can multiply rapidly in the chemically pure water used

to supply hemodialysis systems. It has also been demonstrated clearly that endotoxins and

endotoxin fragments can cross both low-flux and high-flux hemodialysis membranes.

Because 48 hours can elapse between sampling water to determine microbial contamination and

receiving results, and because bacterial proliferation can be rapid, action levels for microbial

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counts and endotoxin concentrations are included in these regulations. Those action levels allow

the user to initiate corrective action before levels exceed the recommended maximum levels.

Unlike cultures, endotoxin testing does not require extended incubation times. Endotoxin testing,

when performed in the dialysis facility, can yield results in approximately 1 hour, thereby

eliminating the long delay between sampling and obtaining a result.

During the development of this recommended practice, the AAMI RDD Committee was tasked

with recommending levels of bacteria and endotoxins above which the water should not be used

for dialysis applications. In making the recommendations outlined in ANSI/AAMI RD52:2004,

Section 4.1.2, the AAMI RDD Committee understood that dialysis would continue at contaminant

levels above the action level but below the recommended maximum level. Establishing a

recommended maximum level of contamination at which dialysis should be stopped immediately

is difficult because the risk of adverse events, such as pyrogenic reactions, must be balanced

against the risks of uremia if a patient is not dialyzed. The balance between these two risks will

depend on the level of contamination, the time of exposure, and the patient's medical condition.

Because this balance will almost certainly vary from circumstance to circumstance, the AAMI

RDD Committee felt that there was insufficient data on which to base levels of bacteria and

endotoxins above which dialysis should not be performed. The final decision of whether to

discontinue dialysis rests with the medical director of a facility. Whatever decision is made, the

AAMI RDD Committee recommends that the water treatment and distribution system be

disinfected promptly any time the levels of bacteria or endotoxins exceed the action levels

recommended in AAMI 4.1.2. Additionally, it may be prudent to discontinue dialyzer reuse if the

levels of bacteria or endotoxins exceed the recommended maximum levels outlined in AAMI

4.1.2, as the water is introduced directly into the blood compartment of the dialyzer.

Additional Guidance:

If the facility reaches the “action” level, remedial action is required. Action could be to repeat a

culture, particularly if only one in a set of cultures was above the action limit. Action could also

include disinfecting the system and repeating cultures at several sites.

Some states require this testing to be done in a laboratory approved for the analysis of potable

water.