ASP Sterrad Velocity Reader, User Manual

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Operation
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STERRAD VELOCITY Reader User’s Guide 29
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Note:
The STERRAD VELOCITY Reader can detect residual enzyme activity even
when the G. stearothermophilus spores are damaged to the point they will not
grow. Therefore, a BI may read as fluorescence-positive even when it is visually
growth-negative. This characteristic of the enzyme response provides an increased
margin of safety and meets the criteria of the FDA reduced incubation time protocol
(greater than 97% correlation between BIs that are growth-positive at 5-7 days
post-sterilization and BIs that are read as fluorescence-positive at 15 minutes).
Check the CI, on the top of the cap, for color change from red/pink to yellow to
confirm that the BI has been exposed to hydrogen peroxide. Incubate the test BI and a
positive control at 55–60°C (131–140°F) for 5 to 7 days. After incubation, inspect the
growth medium in the processed BI for color change from purple to yellow. Compare the
processed BI with the positive control and record results.
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Note:
For easier color comparison, observe the BIs against a white background.
The absence of a color change of the growth medium in the processed BI (i.e.
the growth medium remains purple as compared to an unprocessed uncrushed BI)
indicates that a sterilization condition was achieved (sufficient to kill at least one
million of the most resistant identified bacterial spores in the BI).
Color change from purple to yellow of the growth medium in the processed BI
(as compared to the positive control BI) indicates that a sterilization condition was
not achieved.