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3M™ Attest™ Super Rapid Readout
Biological Indicator 1491
Product Description
The 3M™ Attest™ Super Rapid
Readout Biological Indicator
1491 (blue cap, referred to
hereinafter as the 1491 BI) is a
self-contained biological indicator
specifically designed for rapid
and reliable qualification testing
and routine monitoring of 270°F
(132°C) and 275°F (135°C)
gravity-displacement steam
sterilization processes when
used in conjunction with the
3M™ Attest™ Auto-reader 490
(hereinafter referred to as
the 490 Auto-reader), a
3M™ Attest™ Auto-reader 490H
having software version 4.0.0 or
greater (hereinafter referred to as
the 490H Auto-reader), or a 3M™
Attest™ Mini Auto-reader 490M
(hereinafter referred to as the
490M Auto-reader). The 1491 BI is a single-use device.
A schematic illustrating the design of the 1491 BI is provided in Figure 1.
The self-contained design includes a spore carrier with spores of Geobacillus
stearothermophilus (formerly known as Bacillus stearothermophilus) and a media
ampoule containing bacteriological media which meets the requirements for growth
promoting ability. The spore carrier and media ampoule are contained in a plastic
vial topped with a blue cap. A chemical process indicator which changes from pink
to light brown or darker upon exposure to steam is located on the top of the cap.
The 1491 BI utilizes the ⍺‑glucosidase enzyme system, which is generated naturally
within growing cells of Geobacillus stearothermophilus. The ⍺‑glucosidase in its
active state is detected by measuring the fluorescence produced by the enzymatic
hydrolysis of a non-fluorescent substrate, 4-methylumbelliferyl‑⍺‑D-glucoside
(MUG). The resultant fluorescent by-product, 4-methylumbelliferone (MU) is detected
in the 490 Auto-reader. The presence of fluorescence within the specified incubation
time of the 1491 BI in the 490, 490H, or 490M Auto-reader indicates a steam
sterilization process failure.
PROCESS INDICATOR
BI CAP WITH LABEL
VIAL
MEDIA AMPOULE
AMPOULE CRUSHER
NONWOVEN MATERIAL
GROWTH CHAMBER
SPORE CARRIER
Figure 1: 3M™ Attest™ Super Rapid Readout
Biological Indicator 1491 Design
The 1491 BI can also indicate the presence of G. stearothermophilus organisms by
a visual pH color change reaction. Biochemical activity of the G. stearothermophilus
organism produces metabolic by-products that cause the media to change color
from purple to yellow which would also indicate a steam sterilization process failure.
Use of this indication method is optional and is typically restricted to special studies.
1491 BIs meet ISO 11138-1:2017 and ISO 11138-3:2017.
Readout Times
The super rapid readout and the optional 24-hour visual pH color change incubation
times have been correlated with a 7-day incubation period following the FDA's
Reduced Incubation Time protocol. Processed indicators were examined at 24 hours
and 7 days for detection of a visual pH color change. The fluorescent results and
the 24-hour visual pH color change readings were compared to the 7-day visual
pH color change readings to determine the readout time of the indicator. The time
to a fluorescent result is determined by the software version programmed on the
Auto-reader.
24-minute Fluorescent Result
1491 BIs incubated in a 490 or 490H Auto-reader having software version
4.0.0 or greater or in a 490M Auto-reader have a 24-minute reduced incubation
time result that correlates to the 7-day (168 hours) visual readout result ≥97%
of the time.
30-minute Fluorescent Result
1491 BIs incubated in a 490 Auto-reader having a software version less than
4.0.0 have a 30-minute reduced incubation time result that correlates to the
7-day (168 hours) visual readout result ≥97% of the time.
24-hour Visual pH Color Change Result
1491 BIs incubated in a 490, 490H, or 490M Auto-reader have 24-hour reduced
incubation time results that correlate to the 7-day (168 hours) visual readout
result ≥ 97% of the time.
Due to the high reliability of the fluorescent result there is no advantage to
incubating 1491 BIs after the fluorescent result has been determined by the
490, 490H, or 490M Auto-reader and recorded.
Note: To determine the software version on a 490 or 490H Auto-reader, depress the
Information Button once. The Auto-reader will display two lines of text on the LCD
display. The top row indicates (left to right):
• Serial number
• Software version (V X.Y.Z)
• Current date and time.
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