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8. To activate the biological
indicator, place it in an Attest™
Biological Indicator Activator.
Close and squeeze the activator
to close the 1491 BI cap and
crush the media ampoule. Then
remove the BI and flick it (see
pictures at right). Visually verify
that media has flowed into the
growth chamber at the bottom of
the vial. If the media hasn't filled
the growth chamber, hold the BI
by the cap and flick it until media
fills the growth chamber. Place
the activated 1491 BI:
− in any well of a 490 or 490H
Auto-reader having software
version 4.0.0 or greater
or
− in an incubation well of a
490 Auto-reader having
software version less than
4.0.0 which is color-coded
blue (i.e., configured to
incubate 1491 BIs)
and wait for the result. See the
Auto-reader Operator's Manual
for further information related
to its use.
9. Each day that a processed 1491 BI is incubated, activate and incubate at least
one non-processed 1491 BI to use as a positive control. Follow the activation
instructions provided in Step 8 above. Write a "C" (for "control") and the date
on the BI label. The positive control should be from the same lot code as the
processed biological indicator. It is a good practice to use a positive control each
day a processed 1491 BI is incubated. This helps confirm:
• correct incubation temperatures are met,
• viability of spores has not been altered due to improper storage temperature,
humidity or proximity to chemicals,
• capability of media to promote rapid growth, and
• proper functioning of the Auto-reader.
10. Incubation and Reading:
Incubate the positive control and steam processed 1491 BIs in a
490 Auto-reader or a 490H Auto-reader having software version
4.0.0 or greater.
See the Auto-reader Operator's Manual for the proper use of this equipment.
The Auto-reader will indicate a positive result as soon as it is obtained. The final
negative 1491 BI reading is made at:
− 24 minutes in 490 or 490H Auto-readers having software version
4.0.0 or greater.
− 30 minutes in 490 Auto-readers having software version less than 4.0.0.
After the results are displayed and recorded, the 1491 BIs may be discarded.
Interpretation of Results:
Fluorescent Results
The positive control (unprocessed) 1491 BI must provide a positive fluorescent result
(+ on the 490 or 490H Auto-reader LCD Display). Processed 1491 BI results are
not valid until the positive control reads fluorescent positive. If the positive control
reads negative (- on the LCD Display), check the Auto-reader Operator's Manual
Troubleshooting Guide. Retest the Auto-reader with a new positive control.
With processed 1491 BIs, a positive (+ on the LCD Display) result indicates a
sterilization process failure. A final negative processed 1491 BI reading (- on
the LCD Display) after the specified incubation time indicates an acceptable
sterilization process.
Act immediately on any positive BI results. Determine the cause of the positive BI
following facility policies and procedures. Always retest the sterilizer and do not use
sterilizer for processing loads until three consecutive BI results are negative.
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