CRE Detection via DNA Intercalating Dyes and qPCR
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Solution Overview
Problem
Current methods for detecting live carbapenem-resistant Enterobacteriaceae (CRE) on medical devices like duodenoscopes are labor-intensive, prone to false positives, and lack real-time monitoring capabilities, posing a significant public health risk due to limited treatment options and high mortality rates associated with nosocomial infections.
Innovation Solution
A method involving DNA intercalating dyes like propidium monoazide (PMA) and ethidium monoazide, combined with real-time PCR, to differentiate between live and dead CRE by selectively permeating dead cells and using CRE-specific oligonucleotide primers and probes for accurate detection and quantification within a few hours.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If culture-based monitoring methods are used to detect CRE on medical devices, then detection capability is provided, but the process becomes labor-intensive and time-consuming
Solution Approach 1:
The patent replaces traditional mechanical culture-based detection methods with a molecular biology-based real-time PCR system. This substitution eliminates the need for manual culture procedures, incubation, and colony counting, thereby resolving the contradiction between maintaining detection reliability and improving monitoring efficiency.
Solution Approach 2:
The patent introduces DNA intercalating dyes (PMA or EMA) as intermediaries that selectively bind to DNA in dead bacterial cells. This intermediary enables the differentiation between live and dead CRE, allowing the real-time PCR system to specifically detect viable pathogens while excluding dead cell DNA, thus maintaining detection accuracy while enabling rapid automated processing.
2Reliability
If culture-based monitoring is used, then CRE detection is achieved, but false positives occur due to non-pathogenic environmental contaminants
Solution Approach 1:
The patent applies local quality by making the DNA detection capability selective through the use of intercalating dyes. The dyes selectively interact with DNA in dead cells versus live cells, creating a localized chemical environment that enables specific detection. This selectivity allows the system to distinguish pathogenic CRE from non-pathogenic contaminants, resolving the contradiction between detection accuracy and false positive reduction.
Solution Approach 2:
The patent changes the chemical parameter of DNA detectability by treating samples with DNA intercalating dyes followed by light exposure. This parameter change converts non-detectable dead cell DNA into detectable forms, while live cell DNA remains protected. This enables the system to precisely measure only viable CRE, eliminating false positives from environmental contaminants.
3Object-affected harmful factors
If chemical sterilization techniques are implemented, then CRE transmission risk is reduced, but operational complexity and cost increase
Solution Approach 1:
The patent implements preliminary action by performing real-time detection of CRE on medical devices before they are used on patients. This advance detection allows for targeted sterilization only when necessary, rather than routine sterilization of all devices. By detecting CRE presence beforehand, the system reduces transmission risk while avoiding unnecessary sterilization processes, thereby simplifying overall operational complexity.
4Loss of time
If real-time detection of live CRE is achieved, then rapid response is enabled, but detection method complexity increases
Solution Approach 1:
The patent merges multiple functions into a single integrated real-time PCR assay: (1) DNA extraction from clinical samples, (2) selective differentiation of live versus dead CRE using intercalating dyes, (3) amplification of target DNA sequences, and (4) quantification of live CRE. This consolidation enables rapid detection within hours while managing complexity through systematic integration of procedures.
Solution Approach 2:
The patent uses DNA intercalating dyes as intermediaries that facilitate the differentiation between live and dead CRE. These dyes serve as chemical mediators that selectively bind to DNA in dead cells, enabling the PCR system to distinguish viable pathogens from non-viable cells. This intermediary approach enables rapid accurate detection without requiring complex culturing procedures.
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
This approach enables reliable, real-time monitoring and rapid detection of live CRE on medical devices, reducing the risk of nosocomial infections by providing accurate and reproducible results within 2-3 hours, even in settings without access to reference laboratories or chemical sterilization facilities.
Implementation Method 1
incubating the sample in the presence of a DNA intercalating dye that selectively permeates into dead bacterial cells
Implementation Method 2
a DNA intercalating dye that selectively permeates into dead bacterial cells
Implementation Method 3
exposing the contacted sample to light for about 15 minutes to obtain a light-treated, dye-treated sample
Implementation Method 4
performing a real-time PCR reaction to amplify nucleic acids of the extracted gDNA
Implementation Method 5
a fluorescently labeled oligonucleotide probe to the extracted gDNA
Data Source
AI summary
Provided herein are qPCR-based methods for quantitatively detecting and differentiating between live and dead pathogenic bacteria such as carbapenem-resistant Enterobacteriaceae (CRE). Also provided herein are simple, fast, and reliable genomic DNA extraction methods with improved efficiency.