Biological indicators, and systems and methods for determining efficacy of sterilization
A biological indicator includes: a BI housing; a germinant container inside the BI housing and housing a germinant composition; a germinant releaser configured to release the germinant composition from the germinant container; a germinant releaser support supporting the germinant releaser and configured to bring the germinant releaser into contact with the germinant container upon application of a force to the germinant releaser support or the germinant container; a first spore carrier inside the BI housing, the first spore carrier having a plurality of spores deposited at a first surface thereof; and an imaging window at a first surface of the BI housing. A BI reader is configured to detect and quantify the presence of live spores in the BI, and includes an excitation source, a camera for capturing images of the spores over time, and a processor for analyzing the images to determine the presence of live spores.
1 . A method of determining the efficacy of a sterilization process, the method comprising:
providing a biological indicator, the biological indicator having previously been exposed to the sterilization process, the biological indicator comprising a plurality of spores deposited on a spore carrier and a germinant container housing a germinant composition;
heating the biological indicator to an incubation temperature of the spores;
placing the biological indicator in a BI bay of a BI reader, and using the BI reader to break a seal on an outer surface of the biological indicator, and to release the germinant composition from the germinant container into the biological indicator such that the germinant composition interacts with the plurality of spores on the spore carrier;
emitting light from an excitation source through a window of the biological indicator;
exposing a camera at regular intervals to capture a plurality of images of the spore carrier over time from light emitted back through the window of the biological indicator; and
comparing the plurality of images of the spore carrier to each other with respect to time to determine whether there is a change in the intensity of the light emitted back through the window of the biological indicator over time, the comparing the plurality of images over time comprising identifying an increase in a local light intensity over time at one or more discrete locations on the plurality of images, wherein an increase in the local light intensity over time is interpreted as survival of a spore and a failed sterilization cycle.
2 . The method of claim 1 , wherein the biological indicator comprises a plurality of biological indicators, the method further comprising:
moving the excitation source between each of the biological indicators of the plurality of biological indicators.
3 . The method of claim 1 , wherein the comparing the plurality of images with respect to time comprises comparing the images pixel-by-pixel.
4 . The method of claim 1 , wherein the spore carrier is substantially planar and carries the plurality of spores on a first side thereof, wherein the emitting light from the excitation source through the window of the biological indicator comprises emitting light against the first side of the spore carrier.
5 . The method of claim 4 , wherein the first side of the spore carrier is positioned against the window of the biological indicator.
6 . The method of claim 1 , wherein the spore carrier is substantially planar and carries the plurality of spores on a first side thereof, and the capturing of said plurality of images over time comprises capturing the plurality of images from light emitted by the first side of the spore carrier.
7 . The method of claim 1 , wherein the biological indicator comprises a plurality of biological indicators, the placing the biological indicator in the BI bay of the BI reader comprising placing each of the plurality of biological indicators in a respective BI bay of the BI reader, the method further comprising:
moving the excitation source between the biological indicators in the BI bays;
determining that the excitation source is positioned at one of the BI bays, and in response to said determination (i) emitting light from the excitation source and (ii) receiving and processing the plurality of images from the biological indicator located in the respective BI bay.
8 . The method of claim 1 , wherein the BI bay comprises a plurality of BI bays and the biological indicator is placed in one of the plurality of BI bays of the BI reader, the method further comprising:
moving the excitation source between the plurality of BI bays and turning the excitation source on multiple times under each BI bay during a single cycle, and wherein the camera captures images each time the excitation source is turned on.
9 . The method of claim 1 , wherein the capturing of the plurality of images comprises capturing multiple images of substantially the entire spore carrier.
10 . The method of claim 1 , wherein the spore carrier is substantially planar and carries the plurality of spores on a first side thereof, wherein the comparing the plurality of images comprises comparing a plurality of images of the first side of the spore carrier pixel-by-pixel.
11 . A method of determining the efficacy of a sterilization process, the method comprising:
providing a biological indicator, the biological indicator having previously been exposed to the sterilization process, the biological indicator comprising:
a plurality of spores deposited on a substantially planar spore carrier,
a germinant container housing a germinant composition,
a germinant pad, and
a window,
the germinant pad, the substantially planar spore carrier, and the window being in a stacked arrangement in the biological indicator;
heating the biological indicator to an incubation temperature of the spores;
placing the biological indicator in a BI bay of a BI reader, and using the BI reader to break a seal on an outer surface of the biological indicator, and to release the germinant composition from the germinant container into the biological indicator such that the germinant composition interacts with the plurality of spores on the substantially planar spore carrier;
emitting light from an excitation source through the window of the biological indicator;
exposing a camera at regular intervals to capture a plurality of images of the substantially planar spore carrier over time from light emitted back through the window of the biological indicator; and
comparing the plurality of images of the substantially planar spore carrier to each other with respect to time to determine whether there is a change in the intensity of the light emitted back through the window of the biological indicator over time, the comparing the plurality of images over time comprising identifying an increase in a local light intensity over time at one or more discrete locations on the plurality of images, wherein an increase in the local light intensity over time is interpreted as survival of a spore and a failed sterilization cycle.
12 . The method of claim 11 , wherein the biological indicator comprises a plurality of biological indicators, the method further comprising:
moving the excitation source between each of the biological indicators of the plurality of biological indicators.
13 . The method of claim 11 , wherein the comparing the plurality of images with respect to time comprises comparing the images pixel-by-pixel.
14 . The method of claim 11 , wherein the substantially planar spore carrier carries the plurality of spores on a first side thereof, wherein the emitting light from the excitation source through the window of the biological indicator comprises emitting light against the first side of the substantially planar spore carrier.
15 . The method of claim 14 , wherein the first side of the substantially planar spore carrier is positioned against the window of the biological indicator.
16 . The method of claim 11 , wherein the substantially planar spore carrier carries the plurality of spores on a first side thereof, and the capturing of said plurality of images over time comprises capturing the plurality of images from light emitted by the first side of the substantially planar spore carrier.
17 . The method of claim 11 , wherein the biological indicator comprises a plurality of biological indicators, the placing the biological indicator in the BI bay of the BI reader comprising placing each of the plurality of biological indicators in a respective BI bay of the BI reader, the method further comprising:
moving the excitation source between the biological indicators in the BI bays;
determining that the excitation source is positioned at one of the BI bays, and in response to said determination (i) emitting light from the excitation source and (ii) receiving and processing the plurality of images from the biological indicator located in the respective BI bay.
18 . The method of claim 11 , wherein the BI bay comprises a plurality of BI bays and the biological indicator is placed in one of the plurality of BI bays of the BI reader, the method further comprising:
moving the excitation source between the plurality of BI bays and turning the excitation source on multiple times under each BI bay during a single cycle, and wherein the camera captures images each time the excitation source is turned on.
19 . The method of claim 11 , wherein the capturing of the plurality of images comprises capturing multiple images of substantially the entire substantially planar spore carrier.
20 . The method of claim 11 , wherein the substantially planar spore carrier carries the plurality of spores on a first side thereof, wherein the comparing the plurality of images comprises comparing a plurality of images of the first side of the substantially planar spore carrier pixel-by-pixel.
21 . A method of determining the efficacy of a sterilization process, the method comprising:
providing a biological indicator, the biological indicator having previously been exposed to the sterilization process, the biological indicator comprising:
a plurality of spores deposited on a spore carrier,
a germinant container housing a germinant composition,
a germinant pad, and
a window,
the germinant pad, the spore carrier, the germinant container, and the window being aligned in the biological indicator;
heating the biological indicator to an incubation temperature of the spores;
placing the biological indicator in a BI bay of a BI reader, and using the BI reader to apply pressure towards the germinant container, the germinant pad, the spore carrier, and the window to thereby release the germinant composition from the germinant container into the biological indicator such that the germinant composition interacts with the plurality of spores on the spore carrier;
emitting light from an excitation source through the window of the biological indicator;
exposing a camera at regular intervals to capture a plurality of images of the spore carrier over time from light emitted back through the window of the biological indicator; and
comparing the plurality of images of the spore carrier to each other with respect to time to determine whether there is a change in the intensity of the light emitted back through the window of the biological indicator over time, the comparing the plurality of images over time comprising identifying an increase in a local light intensity over time at one or more discrete locations on the plurality of images, wherein an increase in the local light intensity over time is interpreted as survival of a spore and a failed sterilization cycle.
22 . The method of claim 21 , wherein the biological indicator comprises a plurality of biological indicators, the method further comprising:
moving the excitation source between each of the biological indicators of the plurality of biological indicators.
23 . The method of claim 21 , wherein the comparing the plurality of images with respect to time comprises comparing the images pixel-by-pixel.
24 . The method of claim 21 , wherein the spore carrier is substantially planar and carries the plurality of spores on a first side thereof, and the capturing of said plurality of images over time comprises capturing the plurality of images from light emitted by the first side of the spore carrier.
25 . The method of claim 21 , wherein the biological indicator comprises a plurality of biological indicators, the placing the biological indicator in the BI bay of the BI reader comprising placing each of the plurality of biological indicators in a respective BI bay of the BI reader, the method further comprising:
moving the excitation source between the biological indicators in the BI bays;
determining that the excitation source is positioned at one of the BI bays, and in response to said determination (i) emitting light from the excitation source and (ii) receiving and processing the plurality of images from the biological indicator located in the respective BI bay.
26 . The method of claim 21 , wherein the BI bay comprises a plurality of BI bays and the biological indicator is placed in one of the plurality of BI bays of the BI reader, the method further comprising:
moving the excitation source between the plurality of BI bays and turning the excitation source on multiple times under each BI bay during a single cycle, and wherein the camera captures images each time the excitation source is turned on.
27 . The method of claim 21 , wherein the capturing of the plurality of images comprises capturing multiple images of substantially the entire spore carrier.
28 . The method of claim 21 , wherein the spore carrier is substantially planar and carries the plurality of spores on a first side thereof, wherein the comparing the plurality of images comprises comparing a plurality of images of the first side of the spore carrier pixel-by-pixel.