Flow Cytometry Data Processing for Antimicrobial Sensibility Prediction

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Solution Overview

Problem

Current methods for predicting antibiotic susceptibility in microorganisms using flow cytometry lack robustness and fail to effectively discriminate between susceptible, intermediate, and resistant phenotypes, often relying on average fluorescence intensities and breakpoint concentrations that do not account for heterogeneous population responses.

Innovation Solution

A method and system that utilize a learning stage to generate digital sets of values from microorganisms with diverse phenotypes, creating feature vectors based on fluorescence, forward scatter, and side scatter distributions, and a prediction stage to classify test microorganisms into susceptible, intermediate, or resistant phenotypes using LI-regularized optimization and machine learning models.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If average fluorescence intensity (MFI) values are used for phenotype prediction, then the method is simple to implement, but it masks signals from heterogeneous populations and underestimates subtle variations

Engineering Contradiction:
Improvesimplicity of methodVSAvoiddiscrimination accuracy
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent segments the continuous fluorescence distribution into discrete bins, transforming the data representation from average values to distributed frequency counts. This segmentation allows capture of heterogeneous population responses while maintaining computational tractability through histogram-based feature vectors.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from one-dimensional average MFI values to multi-dimensional histograms that distribute fluorescence values across multiple bins. This dimensional expansion captures the distribution shape and heterogeneity, enabling more accurate phenotype discrimination while preserving operational simplicity through standardized histogram processing.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Ease of operation

If breakpoint concentrations are used for susceptibility testing, then the interpretation is straightforward, but they do not always correlate with early changes detected by FCM and may lose important information

Engineering Contradiction:
Improveinterpretation simplicityVSAvoidearly physiological changes
Core Design Contradiction:
Ease of operationVSLoss of information

Solution Approach 1:

The patent performs preliminary analysis of fluorescence distribution changes at early time points (1-2 hours) before traditional MIC determination. By capturing early physiological responses through histogram analysis, the method predicts final susceptibility outcomes without waiting for complete growth inhibition, preserving information that would be lost in traditional breakpoint-based approaches.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses the shape and distribution of fluorescence histograms as feedback signals to predict susceptibility phenotypes. The histogram distribution patterns provide continuous feedback about population heterogeneity and treatment response, enabling more accurate predictions than discrete breakpoint thresholds while maintaining straightforward interpretation through learned classification models.

Inventive Principle:
Principle #23Feedback

3Device complexity

If only susceptible breakpoint concentrations are used to build prediction models, then the model development is simplified, but the model lacks robustness when validated with different concentrations or strains

Engineering Contradiction:
Improvemodel development complexityVSAvoidmodel robustness
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent develops prediction models using multiple antibiotic concentrations (including sub-inhibitory and supra-inhibitory levels) rather than solely susceptible breakpoints. This multi-concentration approach creates universal models that can robustly predict susceptibility across different strains and validation conditions, as the models learn from diverse response patterns rather than strain-specific breakpoint thresholds.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent varies key parameters including antibiotic concentrations, incubation times, and fluorescence marker types during model development. By training on diverse parameter combinations, the models learn invariant features of susceptibility responses, enhancing robustness when applied to new strains or slightly different experimental conditions while maintaining reasonable development complexity through systematic parameter sampling.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If qualitative region selection is used in 2D matrix analysis, then the method is easy to implement, but the robustness of the method decreases

Engineering Contradiction:
Improveimplementation easeVSAvoidmethod robustness
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces manual qualitative region selection with automated computational algorithms that objectively define discrimination thresholds. Machine learning models automatically learn optimal decision boundaries from training data, eliminating subjectivity and improving robustness while maintaining ease of implementation through automated processing pipelines that require minimal user intervention.

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

Solution Approach 2:

The prediction model performs self-calibration by automatically learning discrimination thresholds from the training dataset without requiring manual region definition. The model serves itself by identifying optimal separation boundaries in the 2D fluorescence space, improving robustness through data-driven threshold selection while preserving operational simplicity through automated model training and validation procedures.

Inventive Principle:
Principle #25Self-service

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 a robust and fast prediction of antibiotic susceptibility phenotypes by capturing subtle variations and integrating multiple concentration data, improving discrimination accuracy and handling heterogeneity in microbial responses.

Implementation Method 1

measuring an optical response to said beam of each of the particles, that is to say its fluorescence

Methodology Applied
Scientific EffectFluorescence: Fluorescence

Implementation Method 2

its forward-scattered light and its side-scattered light

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP3266877B1Flow cytometry data processing for antimicrobial agent sensibility prediction
Publication Date: 2019.02.27 BIOMERIEUX SA
  • EP3266877B1 patent drawingFigure 1~3
  • EP3266877B1 patent drawingFigure 2A~2B
  • EP3266877B1 patent drawingFigure 4A~5C

AI summary

A method for predicting the sensibility phenotype of a test microorganism to an antimicrobial agent amongst susceptible, intermediate and resistant phenotypes, comprising a learning stage and a prediction stage. The learning stage comprises selecting a wide set of different strains having different known sensibility phenotypes determined according EUCAST or CLSI method, acquiring FCM (flow cytometry) distributions for each of said strain aliquoted in liquid samples with fluorescent markers and different concentrations of the antibiotic, and performing a learning machine computing on mono or multidimensional spaces involving feature vectors derived from the FCM acquisition to derive a prediction model of the sensibility phenotype to the antibiotic.