Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving viable micro-organism
Patent
1996-07-12
1998-08-18
Leary, Louise
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving viable micro-organism
435 29, 435839, 435832, 435 4, 435 32, 435808, 435807, 4352525, C12Q 122, C12Q 102, C12Q 118, C12N 100
Patent
active
057957304
DESCRIPTION:
BRIEF SUMMARY
This invention is generally related to both apparatus and methods which use biological indicators to assess or determine the effectiveness of sterilization processes and particularly relates to a rapid method of determining the effectiveness of a sterilization process by correlating a measurement of the germination rate of microbial spores with spore viability.
BACKGROUND
Biological indicators have been used to test and/or determine the effectiveness of sterilization processes. Typically, biological indicators containing microbial spores are exposed to a selected sterilant or sterilizing process and then the survival of any exposed spores is determined by placing the exposed spores in an environment capable of sustaining germination of spores and growth of microbes. In view of the fact that microbial spores are accepted as being much more resistant to sterilization processes than most other types of microorganisms, it is assumed that a sterilization process that will kill microbial spores will also kill any other contaminating microorganisms. See, e.g., Disinfection, Sterilization, and Preservation, Fourth Edition, ed. Block, Seymour S., Lea & Febiger, Chapter 6 (1991) that reports general criteria needed to analyze or assess sterilization processes.
Commonly used biological indicators, due to the need to allow sufficient time for spore outgrowth, have generally required extended periods of incubation time before the effectiveness of a sterilization process may be evaluated. For example, some commercially available indicators require incubation times of 1-2 days before an evaluation of the effectiveness of a sterilization process is available. The reliability of these types of biological indicators is based on a correlation of the results provided by these indicators with the number of spore survivors which are observed after seven days of growth.
The need for a more rapid determination has led to apparatus and procedures which provide an indication of sterilization effectiveness in less time. For example, U.S. Pat. Nos. 5,073,488 and 5,252,484 report methods and apparatus, respectively, that determine the efficacy of a sterilization process in a few hours by assaying microbial enzyme activity that may be correlated with spore or cell viability. In another example, U.S. Pat. No. 5,366,872 reports an assay of certain microbial enzymes in a biological indicator that gives a colored, visually detectable signal that may be related to viable bacteria or microorganisms in a sample after exposure to a sterilization cycle.
Although cell viability after exposure to a variety of sterilants and/or sterilization processes is a traditional measure of sterility, as pointed out above, the effects of such sterilants or sterilization processes on other types of microbial activity has also been investigated. Enzymatic activity has been used to determine the efficacy of a sterilization cycle. In addition, the expression of microbial spore viability, i.e., cell viability, is preceded by spore germination. Spore germination is an irreversible complex series of biochemical events occurring in the first twenty to thirty minutes after microbial spores are exposed to conditions that will support growth of the microbe. In particular, it is believed that germination may be triggered by the presence of specific germinants in the environment. See, e.g., Foster et al., Molec. Biol, 4:137-141 (1990) and Umeda et al., J. Gen. Microbiol., 118:215-221 (1980).
Characteristically, as spores germinate, they absorb water and lose the capability of scattering light in spore-containing suspensions. This property allows germination processes to be followed spectrophotometrically as either a decrease in light absorption or a decrease in light scattering. Specifically, Dadd et al., Journal of Applied Bacteriology, 60:425-433 (1986) have investigated the effects of ethylene oxide sterilization cycles on the germination of Bacillus subtilis spores. Dadd et al. report that Bacillus spores exposed to lethal doses of ethylene oxide do not stop germin
REFERENCES:
patent: 3661717 (1972-05-01), Nelson
patent: 4839291 (1989-06-01), Welsh et al.
patent: 5073488 (1991-12-01), Matner et al.
patent: 5252484 (1993-10-01), Matner et al.
Dadd et al., "Germination of Spores of Bacillus subtilis var. niger Following Exposure to Gaseous Ethylene Oxide", Journal of Applied Bacteriology, 60, pp. 425-433, 1986.
Foster et al., "Pulling the Trigger: The Mechanism of Bacterial Spore Germination", Molecular Microbiology, 4(1), pp. 137-141, 1990.
Fred et al., The Reduction of 2,3,5-Triphenyltetrazolium Chloride by Penicillium chrysogenum, Science, vol. 109, pp. 169-170, Feb. 18, 1949.
Hanlon et al., "Quantitative Assessmemt pf Sterilization Efficiency Using lyophilized Calcium Alginate Biological Indicators", Letters in Applied Microbiology, 17, pp. 171-173, 1993.
Parisi et al., "Sterilization with Ethylene Oxide and Other Gases", Disinfection, Sterilization, and Preservation, Fourth Edition, Chapter 33, pp. 580-595, 1991.
Pflug et al., "Principles of the Thermal Destruction of Microorganisms", Disinfection, Sterilization, and Preservation, Fourth Edition, Chapter 6, pp. 85-128, 1991.
Reich, Robert R., "Effect of Sublethal Ethylene Oxide Exposure on Bacillus subtilis Spores and Biological Indicator Performance", Journal of the Parenteral Drug Association, vol. 34, No. 3, 1980, pp. 200-211.
Rodriguez et al., "Use of a Fluorescent Redox Probe for Direct Visualization of Actively Respiring Bacteria", Applied and Environmental Microbiolgy, vol. 58, No. 6, pp. 1801-1808, Jun. 1992.
Spicher, "Sterilization--The Microbiology Between Claim and Reality", Zbl. Hyg., 194, pp. 223-235, 1993.
Spicher et al., "How Many Biological Indicators Have to be Tested to Make a Reliable Statement as to Their Resistance?", Zbl. Bakt.Hyg., I. Abt. Orig. B 179, pp. 365-380, 1984.
Stellmach et al., "A Flourescent Redox Dye. Influence of Several Substrates and Electron Carriers on the Tetrazolium Salt--Formazan Reaction of Ehrlich Ascites Tumour Cells", Histochemical Journal 19, pp. 21-26, 1987.
Trevors, "Electron Transport System Activity in Soil, Sediment, and Pure Cultures", CRC Critical Reviews in Microbiology, vol. II, Issue 2, pp. 38-101, 1984.
Umeda et al., "Spore Outgrowth and the Development of Flagella in Bacillus subtilis", Journal of General Microbiology, 118, pp. 215-221, 1980.
Urban et al., "Nitroublue Tetrazolium (NBT) Reduction by Bacteria", Acta path, microbiol scand. Sect. B, 87, pp. 227-233, 1979.
Leary Louise
Minnesota Mining and Manufacturing Company
LandOfFree
Rapid read-out biological indicator does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rapid read-out biological indicator, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rapid read-out biological indicator will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1113722