Coupled enzyme-based method for electronic monitoring of biological indicator

Abstract

A sterilization indicator system and method of using the system to determine efficacy of a sterilization process. The system includes a vial having a first compartment containing spores of one or more species of microorganism; a second compartment containing a growth medium with a disaccharide, an oligosaccharide or a polysaccharide in which the vial is free of monosaccharide; an enzyme, capable of acting upon the monosaccharide to yield reaction products and electron transfer, disposed on two or more electrodes adapted to carry an electrical signal resulting from the electron transfer, the pair of electrodes positioned to contact the combined contents of the first compartment and the second compartment during incubation; and an apparatus linked or linkable to the electrodes and adapted to detect and measure the electrical signal resulting from electron transfer when the enzyme acts upon the monosaccharide.

Description

technical field

[0001] The present invention relates to biological indicators for testing the efficacy of sterilization treatments, and more particularly to coupled enzyme-based methods for monitoring such biological indicators in which such monitoring can be performed electronically. Background technique

[0002] Biological indicators (BI) are one of the most important types of indicators. Biological indicators provide the highest degree of assurance that the conditions for sterilization are met within the processor or by the load being processed itself. This type of biological indicator is intended to represent a worst-case scenario for a treatment system by providing within or on the indicator a very large number of organisms that are highly resistant to the particular treatment in question. Often bacterial spores are the organism of choice for monitoring sterilization systems.

[0003] Biological indicators usually consist of microorganisms inoculated onto a carrier ma...

Examples

Embodiment 1

[0082] For illustrative purposes, germinating spores of G. stearothermophilus at E5, E6 and E7 spore populations were monitored over several hours for each reaction containing the growth medium using a Biochemical Analyzer (YSI Instruments) using a glucose electrode. The growth medium consisted of glucose-free tryptone soy broth (TSB) at a concentration of 1 / 8 of the standard TSB concentration (in order to minimize interference from medium components) containing a concentration of 8.5 g / l or 10.5g / l complex sugar maltose. Glucose measurements were taken every 60 minutes. All samples were normalized to the initial glucose reading of the culture medium and observed over an extended time scale, measuring the overall kinetics of the response to the selected conditions. result in Figure 10 Shown in , which shows the effect of spore concentration and maltose concentration on the amount of glucose produced over time.

Embodiment 2

[0084] Evaluation of Geobacillus stearothermophilus spores under E5, E6, and E7 populations in various media formulations to determine how quickly glucose levels are produced when selected levels of maltose are broken down to glucose by viable germination organisms from the spores The presence of living organisms can be detected. The medium was prepared with different concentrations of glucose-free tryptone soy broth ranging from 1 / 8 of the standard glucose-free TSB (tryptone soy broth) concentration to the full standard concentration while keeping the maltose concentration constant at 8.5 g / l. Glucose-free TSB is a general nutrient source for bacteria and it contains casein tryptic digest, soybean papain digest, and salt and buffer; thus, by diluting it, we effectively reduce any interfering groups present in the culture amount of points. "Medium only" samples were monitored throughout the study in order to observe the effect of different concentrations of TSB on the backgr...

Embodiment 3

[0090] 12 containing 2x10 per SCBI 7 A self-contained biological indicator of Geobacillus stearothermophilus of the CPU population was placed in a simulated use medical device load and the full load was processed in a steam sterilizer in a failed (ie, incomplete) cycle. At the completion of the failed cycle, samples were removed and incubated at 56°C for 3 hours. Glucose levels in the medium were evaluated for each sample. Figure 12 is a graph showing the comparison between the signal measured when spores survived the sterilization treatment and the signal measured when no spores survived the sterilization treatment.

technical field

[0001] The present invention relates to biological indicators for testing the efficacy of sterilization treatments, and more particularly to coupled enzyme-based methods for monitoring such biological indicators in which such monitoring can be performed electronically. Background technique

[0002] Biological indicators (BI) are one of the most important types of indicators. Biological indicators provide the highest degree of assurance that the conditions for sterilization are met within the processor or by the load being processed itself. This type of biological indicator is intended to represent a worst-case scenario for a treatment system by providing within or on the indicator a very large number of organisms that are highly resistant to the particular treatment in question. Often bacterial spores are the organism of choice for monitoring sterilization systems.

[0003] Biological indicators usually consist of microorganisms inoculated onto a carrier ma...

Examples

Embodiment 1

[0082] For illustrative purposes, germinating spores of G. stearothermophilus at E5, E6 and E7 spore populations were monitored over several hours for each reaction containing the growth medium using a Biochemical Analyzer (YSI Instruments) using a glucose electrode. The growth medium consisted of glucose-free tryptone soy broth (TSB) at a concentration of 1 / 8 of the standard TSB concentration (in order to minimize interference from medium components) containing a concentration of 8.5 g / l or 10.5g / l complex sugar maltose. Glucose measurements were taken every 60 minutes. All samples were normalized to the initial glucose reading of the culture medium and observed over an extended time scale, measuring the overall kinetics of the response to the selected conditions. result in Figure 10 Shown in , which shows the effect of spore concentration and maltose concentration on the amount of glucose produced over time.

Embodiment 2

[0084] Evaluation of Geobacillus stearothermophilus spores under E5, E6, and E7 populations in various media formulations to determine how quickly glucose levels are produced when selected levels of maltose are broken down to glucose by viable germination organisms from the spores The presence of living organisms can be detected. The medium was prepared with different concentrations of glucose-free tryptone soy broth ranging from 1 / 8 of the standard glucose-free TSB (tryptone soy broth) concentration to the full standard concentration while keeping the maltose concentration constant at 8.5 g / l. Glucose-free TSB is a general nutrient source for bacteria and it contains casein tryptic digest, soybean papain digest, and salt and buffer; thus, by diluting it, we effectively reduce any interfering groups present in the culture amount of points. "Medium only" samples were monitored throughout the study in order to observe the effect of different concentrations of TSB on the backgr...

Embodiment 3

[0090] 12 containing 2x10 per SCBI 7 A self-contained biological indicator of Geobacillus stearothermophilus of the CPU population was placed in a simulated use medical device load and the full load was processed in a steam sterilizer in a failed (ie, incomplete) cycle. At the completion of the failed cycle, samples were removed and incubated at 56°C for 3 hours. Glucose levels in the medium were evaluated for each sample. Figure 12 is a graph showing the comparison between the signal measured when spores survived the sterilization treatment and the signal measured when no spores survived the sterilization treatment.

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