Droplet Digital PCR Assays for Fastidious Pathogen Detection
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Solution Overview
Problem
Current diagnostic methods for detecting fastidious microorganisms like Bartonella and Borrelia are hindered by low bacterial loads, long growth times, and PCR-inhibitory components in biological samples, leading to poor sensitivity and complexity in clinical diagnosis.
Innovation Solution
The implementation of a droplet digital PCR (ddPCR) method that distributes nucleic acids from samples into microfluidic partitions for amplification, using a water-oil emulsion technology to reduce inhibitory substances and enhance sensitivity, allowing for precise detection and identification of fastidious microorganisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PCR methods are used to detect fastidious microorganisms, then the detection process is simpler, but the sensitivity is poor due to low bacterial loads and PCR-inhibitory components in biological samples
Solution Approach 1:
The patent applies segmentation by partitioning the sample into numerous individual droplets, each containing a small volume of the original sample mixed with PCR reagents. This segmentation isolates target nucleic acids into discrete compartments, enabling digital counting of positive droplets to achieve absolute quantification without standard curves, thereby improving detection sensitivity while managing complexity through automated microfluidic partitioning systems
Solution Approach 2:
The patent uses an intermediary approach by introducing a water-oil emulsion system as a mediator between the sample and detection process. The oil phase acts as an inert matrix that isolates individual water-containing droplets, preventing cross-contamination and reducing the impact of PCR-inhibitory substances present in biological samples, thus improving detection sensitivity without requiring complex sample purification steps
2Measurement precision
If standard curve-based quantification is used in conventional PCR, then the quantification process is established, but it requires additional standards and calibration steps increasing complexity
Solution Approach 1:
The patent applies self-service by enabling the system to perform absolute quantification without external standards or calibration curves. By partitioning the sample into many droplets and counting the number of positive droplets, the system directly calculates the concentration of target nucleic acid based on Poisson statistics, eliminating the need for separate standard curve preparation and simplifying the quantification process while maintaining high accuracy
Solution Approach 2:
The patent uses preliminary action by pre-partitioning the sample into a large number of individual droplets before the PCR amplification step. This preliminary partitioning allows the system to capture the distribution of target molecules across many compartments, enabling direct digital counting and absolute quantification without requiring subsequent calibration steps, thus reducing overall process complexity
3Productivity
If PCR amplification is performed on undiluted biological samples, then the detection process is faster, but inhibitory substances compete during amplification reducing sensitivity
Solution Approach 1:
The patent applies the extraction principle by removing inhibitory substances from the reaction environment through the water-oil emulsion partitioning system. Inhibitory components present in undiluted biological samples are diluted and isolated within individual droplets, preventing them from interfering with PCR amplification while maintaining the speed of direct amplification without requiring extensive sample purification steps
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 significantly improves the detection sensitivity and specificity for Bartonella and Borrelia species, enabling earlier and more accurate diagnosis by minimizing the impact of inhibitors and reducing the need for standard curves, thus facilitating better clinical management of infections.
Implementation Method 1
uses a water-oil emulsion technology driven by microfluidics and surfactant chemistry to massively partition samples into 15,000 to 20,000 1 ηL sized droplets
Implementation Method 2
amplification of DNA within each drop is recorded using fluorescently labeled probe detection
Data Source
AI summary
Provided herein are compositions, methods, and kits for detecting the presence of and/or identifying fastidious microorganisms, such as Bartonella spp., Borrelia spp., Anaplasma spp., Ehrlichia spp., Babesia/Theileria spp., Rickettsia spp., and/or Mycoplasma spp., in a sample. The compositions, methods and kits of the inventive concept include use of droplet digital PCR (ddPCR) assays for the detection and quantitation of the fastidious microorganisms.