CROSS-REFERENCE TO CO-PENDING APPLICATION

This application is a counterpart of U.S. patent application Ser. No. 15/057,768, filed Mar. 1, 2016, and Ser. No. 15/397,018, filed Jan. 31, 2017, both of which are incorporated by reference their entirety.

FIELD

The subject matter disclosed herein relates to self-contained biological sterilization indicators.

BACKGROUND

A sterilization indicator is a device that may be placed alongside or in proximity to a medical device being subject to a sterilization cycle, such that the sterilization indicator is subject to the same sterilization cycle as the medical device. For instance, a biological indictor having a predetermined quantity of microorganisms possessing known resistance to the sterilant may be placed into a sterilization chamber alongside a medical device and subjected to a sterilization cycle. After the cycle is complete, the microorganisms in the biological indicator may be cultured to determine whether any of the microorganisms survived the cycle.

Certain biological indicators are referred to as being “self-contained.” These biological indicators typically include a housing that contains a quantity of microorganisms and a source of growth media in a frangible container that is located near the microorganisms. Like other biological indicators, the “self-contained” biological indicator (“SCBI”) may be subject to a sterilization cycle alongside medical devices. Following the cycle, the frangible container may be broken to release the growth media and culture any surviving microorganisms in situ. The SCBI may be incubated at elevated temperatures, typically around 50° C. to 60° C., which encourages outgrowth of the surviving microorganisms.

After incubation, the SCBI is analyzed to detect the presence of microorganisms. Should any microorganisms be detected, the sterilization cycle may be considered to have been ineffective. Should no microorganisms be detected, the sterilization cycle may be considered to have been effective. Some SCBIs are designed to incorporate a growth medium that changes color in the presence of microorganisms. This color change may be due to a shift in pH that occurs due to acid production by live microorganisms that metabolize a growth medium, which also contains a pH indicating dye. Other SCBIs are designed to incorporate a growth medium that includes a fluorophore whose fluorescence depends on the amount of viable microorganisms contained in the medium. For these SCBIs, a color change or change in the amount of fluorescence indicates that surviving microorganisms may have multiplied during incubation.

SUMMARY

A self-contained biological indicator (“SCBI”) is disclosed. The SCBI may include a first ampule having a first top and a first bottom. The SCBI may also include a second ampule having a second top and a second bottom. The first ampule may contain a first volume of a first growth medium, and the second ampule may contain a second volume of a second growth medium. The first ampule may be disposed adjacent to the second ampule. The SCBI may also include a cap, which may be disposed above the first ampule and the second ampule. The first top of the first ampule may be disposed closer to the cap than the second top of the second ampule. In some embodiments, the first top may contact the cap. The SCBI may also include an insert, at least a portion of which may be disposed below and in contact with the first ampule and the second ampule.

In some embodiments, the first ampule may be longer than the second ampule. For example, the first ampule may be between approximately 0.5 inches and 1.5 inches longer than the second ampule. The first ampule may be approximately 1 inch longer than the second ampule. In some embodiments, the insert may include a first surface and a second surface that is parallel or substantially parallel to the first surface and further from the cap than the first surface. In these embodiments, the first bottom may contact the first surface and the second bottom may contact the second surface. The first surface may be disposed between approximately 0.1 inches to 1.5 inches above the second surface. The first surface may be disposed approximately 0.8 inches above the second surface.

In some embodiments, the first growth medium is the same as the second growth medium. For example, the first growth medium and the second growth medium may include 4-methylumbelliferyl α-D-glucoside (MUG). The first volume of the first growth medium may be less than the second volume of the second growth medium. The first volume may be between approximately 50 μl and 150 μl and the second volume may be greater than approximately 150 μl. The first volume may be approximately 100 μl and the second volume may be approximately 300 μl.

The SCBI may also include a vial coupled to the cap. At least a portion of the first ampule and a portion of the second ampule may be disposed within the vail. The vial and cap may include tongue and a groove features. The vial may alternatively or additionally include a stop surface surrounding a portion of the vial and disposed between approximately 0.1 inches and 1.5 inches below a rim of the cap. For example, the stop surface may be disposed approximately 0.8 inches from the rim of the cap.

The SCBI may be used to determine whether a sterilization cycle is efficacious. The SCBI may be subjected to the sterilization cycle. Then, the first ampule may be broken. The SCBI may be analyzed for changes in fluorescence of the first growth medium. Then, the second ampule may be broken. The SCBI may be analyzed for changes in a color of the second growth medium. In some exemplary versions of this method, the step of breaking the first ampule includes depressing the cap from the first position toward a second position, and the step of breaking the second ampule includes depressing the cap from the second position toward a third position.

