What can cause the Rosolic Acid media for the m-FC test to turn pink but not exhibit any growth?

Document ID

Document ID TE5316

Published Date

Published Date 25/01/2018
Question
What can cause the Rosolic Acid media for the m-FC test to turn pink but not exhibit any growth?
Summary
m-FC Rosolic acid media (catalog number/order code 2428550) turns pink with no growth
Answer

While we have noted this phenomenon in the past, unfortunately the exact cause is unknown. Our microbiology team has seen pink plates in years past, but we have not been able to intentionally duplicate (with any particular organism, including Pseudomonas or Bacillus) this color formation in the lab.

There is a theory that irradiated plates with absorbant pads may be interacting with the media or the organisms even though there isn't any growth to cause the pink color. We currently use Ethylene Oxide sterilized plates with pads, and since this switch from a couple years ago, there has been no reoccurances of the pink color formation in our labs.