Environmental monitoring: viable particles

The Question posed on LinkedIn.

“Hi all, I would like to ask you about how to perform cleanroom microbiological environmental monitoring. Is it clearly defined in guides?
TSA and Sab at different temperatures or only TSA? If only one TSA plate, do you incubate at 20-25ºC and then at 30-35ºC, or only at one temperature?
Do you performe growth promotion test in same conditions?
Thank you for your comments!”

My advice:

USP <791> Environmental Monitoring Program Design and Application

USP <1116> Microbiological Control and Monitoring of Aseptic Processing Environments states “….time & incubation temps is made once…media have been selected. Typically…22.5 ± 2.5 and 32.5 ± 2.5…incubation time of 72 & 48 hrs, respectively. Sterilization processes used to prepare growth media for the environmental program should be validated &…media should be examined for sterility & for growth promotion as indicated under Sterility Tests 71. In addition, for the Growth Promotion test, representative microflora isolated from the controlled environment or ATCC strain preparations of these isolates may also be used to test media. Media must be able to support growth when inoculated with less than 100 colony-forming units (cfu) of the challenge organisms.”

So, pick your media. Test it. After that, validate your sampling recovery methods.