Self-contained Biological Indicator for Sterilization Validation
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Solution Overview
Problem
Current biological indicators are specific to particular sterilization cycles and cannot be used across various sterilization conditions, including steam, ethylene oxide, and other sterilants, making them ineffective for validating the efficacy of different sterilization processes.
Innovation Solution
Development of self-contained biological indicators that can determine the efficacy of multiple sterilization cycles, including steam sterilization cycles with varying temperatures and modalities, using bacterial spores capable of producing an enzyme that catalyzes the cleavage of a fluorogenic substrate, producing a fluorescently detectable compound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional biological indicators are designed for specific sterilization cycles, then they can accurately evaluate the effectiveness of that particular cycle, but they cannot be used across various sterilization conditions (steam, ethylene oxide, radiation, etc.)
Solution Approach 1:
The patent creates a universal biological indicator system that can evaluate multiple sterilization methods (steam, ethylene oxide, radiation, chemical) using a single indicator type. The indicator contains spores of microorganisms with enzymes that respond to different sterilization conditions through a common fluorescent substrate detection system, eliminating the need for separate indicators for each sterilization method.
Solution Approach 2:
The patent employs a fluorescent substrate that changes its fluorescent properties in response to different sterilization conditions. The enzyme produced by the spores catalyzes the cleavage of this substrate, producing a fluorescent compound whose detection indicates spore survival. This parameter change approach allows the same indicator to distinguish between different sterilization effectiveness levels across various methods.
2Reliability
If conventional biological indicators use spore incubation in nutrient medium to determine survival, then they can reliably detect surviving spores, but the readout time can take up to 24 hours
Solution Approach 1:
The patent incorporates a fluorescent substrate and enzyme system into the biological indicator before sterilization. The spores are pre-loaded with the enzyme capability, and the fluorescent substrate is pre-positioned in the indicator. After sterilization, if spores survive, they immediately begin catalyzing the substrate cleavage reaction, which produces a detectable fluorescent signal without requiring extended incubation periods.
Solution Approach 2:
The patent replaces the conventional mechanical/incubation-based detection method with a biochemical fluorescence detection system. Instead of relying on slow microbial growth and colony formation in nutrient media, the system uses enzyme-catalyzed chemical reactions that produce fluorescent compounds detectable within minutes to hours, dramatically reducing readout time while maintaining reliability.
3Adaptability or versatility
If a single biological indicator is designed to be universal for all sterilization cycles, then it can be used across different sterilization conditions, but it must be able to respond to varied sterilization temperatures and modalities
Solution Approach 1:
The patent designs a universal biological indicator containing spores of microorganisms that possess enzymes capable of responding to multiple sterilization conditions. The indicator uses a single fluorescent substrate that can be cleaved by these enzymes under various sterilization modalities (steam, ethylene oxide, radiation, chemical), allowing one indicator type to evaluate the effectiveness of any sterilization method without requiring method-specific indicators.
4Loss of time
If rapid readout technology uses fluorescent response during incubation, then the detection time is reduced, but the system requires precise control of pH and other parameters in the growth medium
Solution Approach 1:
The patent combines multiple functions into a single integrated indicator system. The growth medium contains both the fluorescent substrate and the necessary nutrients for spore germination and enzyme activity. The pH control mechanism is integrated into the medium formulation itself, which is designed to maintain optimal conditions for the enzymatic reaction while supporting spore survival and germination. This merging eliminates the need for separate pH control systems or multiple medium components.
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
The self-contained biological indicators can rapidly determine the efficacy of various sterilization cycles, including steam sterilization cycles, in less than 60 minutes, providing a universal solution for validating sterilization processes across different conditions.
Implementation Method 1
bacterial spores capable of producing an enzyme that catalyzes the cleavage of a fluorogenic substrate, producing a fluorescently detectable compound
Implementation Method 2
producing a fluorescently detectable compound
Data Source
AI summary
The present disclosure is directed to self-contained biological indicators wherein a single type of indicator is capable of being used for various sterilization conditions, including sterilization with steam and/or ethylene oxide. In some embodiments, a single type of biological indicator is capable of being used for different steam sterilization conditions having varied temperatures and sterilization cycles.