Oct 14, 2007

Failed a natural product sterility test

One part of the ETO sterilization validation we're performing involves testing the natural product sterility (NPS). This entails sterilizing the medical device and then immersing the device in a media (you can also run the media through the device). Then removing the media and waiting around to see if it grows anything. We had 40 samples tested, which is standard, I'm not sure if they mix the media together or keep it separate while waiting for stuff to grow. By testing the sterility this way you're ensuring that the product is at least as easy to sterilize as known spore strips. Once your sterilization is fully validated you can skip the NPS testing.

Anyway, our natural product sterility sample failed on day 12 of 14, looks like a do-over with some more aggressive sterilization conditions. Even if it is a false positive (day 12!!), it doesn't matter, its a non-sterile load. Resterilization (or actually now just sterilization) is a tricky mix of old full cycles becoming the new partial cycles and the sample requirements cascade from that.

There is a silver lining, we did pass the bacteriostasis/fungistasis test! Actually, while a bit of a downer we had planned for something like this previously and we have to push some things a bit harder- we need to make up some samples, but overall it is not too bad and our timeline is largely intact. My boss has had these things happen with sterilization before so he had us prepared.


Anonymous said...

You should not run your NPRT samples in a half cycle. You should run your NPRT on a fractional (sub half cycle) so if you do get a positive you have not compromised all the historical validation data.

Medical Equipment Supplier said...

Yes I agree with you, "You should run your NPRT on a fractional (sub half cycle) "