Method for monitoring a sterilization process via membrane potential

1. A method for monitoring efficacy of a sterilization process, comprising:

(A) exposing an article to be sterilized and a biological indicator to a sterilization medium during a sterilization process, the biological indicator comprising a cell with a plasma membrane; and

(B) incubating the cell in an incubation medium and measuring the membrane potential of the cell,

wherein when measuring the membrane potential, zero change in the membrane potential indicates efficacy of the sterilization process and any change in the membrane potential indicates failure of the sterilization process.

2. The method of claim 1 , wherein the sterilization medium comprises at least one liquid sterilant.

3. The method of claim 2 , wherein the liquid sterilant comprises peracetic acid, at least one peroxide, or a mixture of two or more thereof.

4. The method of claim 1 , wherein the sterilization medium comprises at least one gaseous sterilant.

5. The method of claim 4 , wherein the gaseous sterilant comprises hydrogen peroxide.

6. The method of claim 5 wherein the gaseous sterilant further comprises ammonia.

7. The method of claim 1 wherein the sterilization medium comprises steam.

8. The method of claim 1 wherein the biological indicator comprises spores.

9. The method of claim 1 wherein the biological indicator comprises bacteria of the Bacillus, Geobacillus or Clostridia genera.

10. The method of claim 1 wherein the biological indicator comprises Geobacillus stearothermophilus, Bacillus atrophaeus, Bacillus subtilis, Bacillus pumilus, Bacillus coagulans, Clostridium sporogenes, Bacillus subtilis globigii, Bacillus cereus, Bacillus circulans , or a mixture of two or more thereof.

11. The method of claim 1 wherein the biological indicator comprises fungi, mycobacteria, protozoa, vegetative bacteria, or a mixture of two or more thereof.

12. The method of claim 1 wherein the biological indicator comprises Aspergillus niger, Candida albicans, Trichophyton mentagrophytes, Wangiella dermatitis, Mycobacterium chelonae, Mycobacterium gordonae, Mycobacterium smegmatis, Mycobacterium terrae, Giardia lamblia, Cryptosporidium parvum, Aeromonas hydrophila, Enterococcus faecalis, Streptococcus faecalis, Enterococcus faecium, Streptococcus pyrogenes, Escherichia coli, Klebsiella ( pneumoniae ), Legionella pneumophila, Methylobacterium, Pseudomonas aeruginosa, Salmonella choleraesuis, Helicobacter pylori, Staphylococcus aureus, Staphylococcus epidermidis, Stenotrophomonas maltophilia , or a mixture of two or more thereof.

13. The method of claim 1 wherein the biological indicator comprises Geobacillus stearothermophilus.

14. The method of claim 1 wherein the biological indicator is incubated in an incubation medium, the biological indicator being incubated in the presence of a membrane potential fluorescent dye.

15. The method of claim 14 wherein the dye is a carbocyanine.

16. The method of claim 14 wherein the dye is an oxonol.

17. The method of claim 14 wherein the dye is 3,3′-dihexyloxycarbocyanine iodine or bis-(1,3-dibutylbarbituric acid)trimethine oxonol.

18. The method of claim 1 wherein the membrane potential is measured using fluorescence polarization.

19. The method of claim 1 wherein the membrane potential is measured using fluorescence resonance energy transfer.

20. The method of claim 1 wherein the cell is a spore of Geobacillus stearothermophilus.

21. The method of claim 1 wherein the incubation medium comprises one or more nutrient sources and one or more microbial recovery, induction or growth indicators.