Clostridium difficile Detection via tcdB Gene Amplification

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Solution Overview

Problem

Current diagnostic tests for Clostridium difficile infections are prone to false positives and false negatives, and there is a need for a more sensitive method that can accurately detect the presence of C. difficile in samples.

Innovation Solution

The method involves using specific primers and probes targeting the C. difficile toxin B (tcdB) gene for amplification and detection, employing PCR and FRET technology to identify the presence or absence of the tcdB gene, which is specific to toxigenic C. difficile strains, thereby reducing cross-reactivity with other Clostridium species.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If commercial diagnostic tests detecting toxins A and B are used, then C. difficile detection can be performed, but false positive and false negative results occur due to cross-reactions and limited sensitivity

Engineering Contradiction:
Improvedetection accuracyVSAvoidtest reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention extracts and targets specifically the tcdB gene sequence from C. difficile bacteria through PCR amplification, rather than detecting toxins produced by the bacteria. This extraction of the specific genetic marker allows for direct detection of the organism itself, eliminating cross-reaction issues with other Clostridium species that produce similar toxins but have different genetic sequences.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention introduces PCR primers and probes as intermediary tools that specifically bind to the tcdB gene sequence. These molecular intermediaries enable indirect detection of C. difficile by amplifying and detecting its unique genetic signature, providing higher specificity than direct toxin detection while maintaining sensitivity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If toxin detection methods are used, then C. difficile infection can be diagnosed, but the sensitivity is insufficient compared to culture methods

Engineering Contradiction:
Improvedetection sensitivityVSAvoiddetection efficiency
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The invention performs preliminary amplification of the target tcdB gene sequence through PCR before detection. This preliminary action increases the amount of target material available for detection, thereby enhancing sensitivity without requiring time-consuming culture steps. The amplification step prepares the sample in advance for highly sensitive probe-based detection.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention replaces the mechanical and time-intensive culture system with a molecular biology-based PCR detection system. This substitution eliminates the need for bacterial cultivation while achieving superior sensitivity through genetic amplification, significantly improving detection efficiency and reducing turnaround time.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If broad-spectrum toxin detection is performed, then all C. difficile strains can be detected, but cross-reaction with other Clostridium species occurs

Engineering Contradiction:
Improvedetection coverageVSAvoidspecificity
Core Design Contradiction:
Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The invention applies local quality by designing primers and probes that target specific regions of the tcdB gene with unique sequence characteristics. Rather than detecting all toxins broadly, the detection system focuses on locally specific genetic sequences that are unique to C. difficile, thereby achieving high specificity while maintaining the ability to detect various C. difficile strains through conserved regions of the gene.

Inventive Principle:
Principle #3Local quality

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 enhances the sensitivity and specificity of C. difficile detection, reducing false positives and negatives, and provides a reliable method for routine clinical diagnosis.

Implementation Method 1

performing at least one cycling step that includes amplifying a portion of a tcdB nucleic acid molecule from a sample

Methodology Applied
Scientific EffectPCR amplification:

Implementation Method 2

detecting the presence or absence of fluorescence resonance energy transfer (FRET) between the donor fluorescent moiety and the acceptor fluorescent moiety of the probe

Methodology Applied
Scientific EffectFluorescence resonance energy transfer (FRET):

Data Source

PatentEP2898095B1Compositions and methods for detection of clostridium difficile
Publication Date: 2019.11.20 ROCHE DIAGNOSTICS GMBH
  • EP2898095B1 patent drawingFigure 1A~1C
  • EP2898095B1 patent drawingFigure 2A
  • EP2898095B1 patent drawingFigure 2B

AI summary

Methods for the rapid detection of the presence or absence of Clostridium difficile in a biological or non-biological sample are described. The methods can include performing an amplifying step, a hybridizing step, and a detecting step. Furthermore, primers, probes, and kits are provided that are designed for the detection of Clostridium difficile.