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Z Series RO System by GE Osmonics
4.5 Product Water Culture
FREQUENCY: A product water culture should be taken once a month or more often,
depending upon culture results, and unit protocol. GE Osmonics recommends this be
performed before and after disinfection.
RATIONALE: Performing a product water culture will help ensure that the microbial
count of the product (RO) water falls within the AAMI Hemodialysis Water Standard.
The AAMI standard maximum allowable concentration for bacteria in product water is
200 colony-forming units. A bacterial count above the maximum level may be harmful
to the hemodialysis patient.
PREPARATION: Consult your lab to find out what type of sterile container, such as
Millipore or 3M Commercial Standard Plate count sampler, to use and how much product
(RO) water is required to perform the test. Make certain that your laboratory is informed
of the correct procedure for performing a product water culture. A "spread plate method"
NOT a "calibrated loop" technique should be used, with tryptic soy agar or equivalent
agar, NOT blood or chocolate agar. If tested incorrectly, the results may be inaccurate.
The sample should be assayed within 30 minutes of obtaining it, or refrigerated (5°C)
immediately and assayed within a 24-hour period. Obtain the samples wearing long
sleeves and a mask using a mid-stream “clean catch” type procedure to prevent
contamination of samples
4.5.1 Product Water Culture Procedure
WARNING:
This procedure must be completed at all points of use (e.g., dialysis stations, re use
stations) on at least a monthly basis.
1. Read and understand all applicable instructions before initiating water culture
procedure.
2. Turn on RO unit. Allow RO unit to run for 10-15 minutes.
3. Using aseptic technique, allow the RO product water to openly flow for
approximately 1 minute.
4. Maintaining aseptic technique, hold the flowing product water over a sterile
container (e.g. Millipore
commercial sampler, or lab recommended).
5. Fill the sterile container with the appropriate amount of RO product water.
Follow the manufacturer’s instructions when using commercial samplers.
6. Aseptically cap the specimen container immediately.
7. Label the specimen appropriately with:
• Test to be performed - "culture / colony count"
• Sample source - product water/RO, machine serial number and room location
• Time and date sample obtained
• Person who obtained specimen
• Any other pertinent information or procedures your facility or lab requires
8. The samples should be assayed within 30 minutes of obtaining or refrigerated at
5° C immediately and assayed within a 24-hour period.
1238339b – 16Oct03 4 - 25 Routine Maintenance