Genetically Engineered Biological Indicator for Rapid Sterilization Testing
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Solution Overview
Problem
Existing sterilization indicators require lengthy incubation periods to confirm sterilization effectiveness, which is impractical for settings with limited resources or urgent reuse needs, and existing rapid detection methods can lead to nuisance failures due to enzyme resistance issues.
Innovation Solution
A genetically engineered biological indicator comprising a test organism with a reporter gene and repressor gene that inhibits enzyme production until exposed to an inducer, allowing for rapid detection of sterilization efficacy by contacting the indicator with a sterilization medium and then an inducer and enzyme substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If classical sterilization indicators using test organisms are used, then sterilization effectiveness can be determined, but the process requires 24 to 72 hours of incubation which is impractical and costly
Solution Approach 1:
The patent extracts the detection function from the test organism itself by introducing a separate reporter organism that produces an enzyme (beta-galactosidase) as a direct indicator of sterilization failure. This separates the testing function from the growth function, allowing rapid enzyme detection without requiring 24-72 hours of incubation for organism growth.
Solution Approach 2:
The patent introduces an intermediary enzyme (beta-galactosidase) produced by the reporter organism that serves as a mediator between sterilization exposure and detectable signal. This enzyme breaks down a chromogenic substrate to produce a visible color change, providing a rapid intermediate detection method that doesn't require waiting for test organism growth.
2Loss of time
If the enzyme alpha glucosidase is used for rapid detection, then detection time is reduced to one hour, but nuisance failures occur because the enzyme is more resistant to heat than the microorganism
Solution Approach 1:
The patent changes the thermal resistance parameter of the indicator system by selecting a reporter organism (Bacillus stearothermophilus) and its enzyme (beta-galactosidase) that have thermal resistance properties matched to the test organism. This ensures both the enzyme and test organism respond similarly to sterilization conditions, eliminating nuisance failures where the enzyme survived but the test organism died.
3Loss of time
If the enzyme alpha glucosidase is present in the spore coat, then detection can occur without metabolism, but the enzyme presence does not directly indicate life and may lead to false positives
Solution Approach 1:
The patent extracts the enzyme production function from the test organism's natural metabolism by using a reporter organism that produces beta-galactosidase as a separate, controllable indicator. This enzyme is produced only when the reporter organism is viable and exposed to the inducer (lactose), providing a direct and unambiguous indication of both viability and metabolic function.
Solution Approach 2:
The patent applies preliminary action by using a repressor protein that prevents enzyme production until the organism is exposed to the inducer after sterilization. This ensures the enzyme is produced only if the organism survived sterilization and is metabolically active, providing a clear preliminary indication of viability before final interpretation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables rapid determination of sterilization effectiveness within hours, eliminating the need for lengthy incubation and reducing nuisance failures by ensuring the indicator enzyme is only produced post-sterilization, thus providing a direct and accurate assessment of sterilization success.
Implementation Method 1
The reporter gene is taken up by the test organism. The repressor gene inhibits expression of the reporter gene until the reporter gene is exposed to at least one inducer. The indicator enzyme breaks down a chromogenic substrate to produce a detectable color change.
Implementation Method 2
The indicator enzyme breaks down a chromogenic substrate to produce a detectable color change.
Data Source
AI summary
The disclosed technology relates to a genetically engineered biological indicator, comprising: at least one test organism and at least one reporter gene suitable for producing an indicator enzyme, the reporter gene being taken up by the test organism; and at least one repressor gene that inhibits expression of the reporter gene until the reporter gene is exposed to at least one inducer. A process and an apparatus for using the biological indicator are disclosed.