Self-contained sterilization indicators including a neutralizer for residual oxidizing sterilant

1. A self-contained sterilization indicator for testing the effectiveness of a sterilization procedure, the self-contained sterilization indicator comprising:

an outer container having at least one opening to allow sterilant to enter the outer container during the sterilization procedure;

a carrier contained within the outer container;

biological material comprising a source of an active enzyme, wherein the source of active enzyme is supported by the carrier; wherein the active enzyme has an enzyme activity that is correlated with the survival of at least one test microorganism commonly used to monitor the effectiveness of a sterilization procedure; wherein the source of an active enzyme is inactivated by a sterilization procedure that is lethal to the test microorganism, but wherein the source of an active enzyme is not inactivated by a sterilization procedure that is sublethal to the test microorganism;

wherein one or more components of the sterilization indicator retains residual oxidizing sterilant;

a neutralizer disposed within the indicator in an amount effective to neutralize residual oxidizing sterilant, wherein the neutralizer is not an enzyme and not a metal catalyst; and

a breakable inner container within the outer container, wherein the inner container:

is impermeable to the sterilant used in the sterilization procedure;

includes an enzyme substrate; and

is adapted so that it may be broken to allow the enzyme substrate to react with active enzyme to form an enzyme-modified product that provides a detectable indication of the failure of a sterilization procedure.

2. The sterilization indicator of claim 1 , wherein the neutralizer is a sulfur-containing compound.

3. The sterilization indicator of claim 2 , wherein the sulfur-containing compound is selected from the group consisting of methionine, L-cysteine, D-ethionine, S-methyl-L-cysteine, S-benzyl-L-cysteine, sodium thiosulfate, glutathionine, L-cystathionine, N-acetyl-L-cysteine, carboxymethylcysteine, D,L-homocysteine, D,L-homocysteine-thiolactone, thiodipropionic acid, and combinations thereof.

4. The sterilization indicator of claim 1 , wherein the neutralizer is a non-sulfur-containing compound.

5. The sterilization indicator of claim 1 , wherein the neutralizer is isolated from the sterilant during sterilization.

6. The sterilization indicator of claim 1 , wherein the carrier comprises a material in a sheet form.

7. The sterilization indicator of claim 1 , wherein the carrier comprises a porous carrier and the biological material is distributed within the carrier.

8. The sterilization indicator of claim 7 , wherein the porous carrier occupies at least 5% of the volume of the container in which it is located.

9. The sterilization indicator of claim 7 , wherein the porous carrier occupies no more than 50% of the volume of the container.

10. The sterilization indicator of claim 8 , wherein the porous carrier has a solidity of greater than 5%.

11. The sterilization indicator of claim 8 , wherein the porous carrier has an effective fiber diameter of greater than 10 microns.

12. The sterilization indicator of claim 1 , wherein the carrier retains residual oxidizing sterilant.

13. The sterilization indicator of claim 1 , wherein the carrier comprises a hydrophobic material.

14. The sterilization indicator of claim 1 , wherein the carrier comprises a hydrophilic material.

15. The sterilization indicator of claim 1 , wherein the detectable indication of the failure of a sterilization procedure comprises a detectable fluorescence, luminescence, and/or chromogenic indication.

16. The sterilization indicator of claim 1 , wherein the oxidizing sterilant comprises hydrogen peroxide vapor.