Flow Cytometry Antimicrobial Quantification
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Solution Overview
Problem
Current therapeutic drug monitoring (TDM) methods for antimicrobials are limited by their availability for only a narrow selection of antibiotics, high costs, and inability to assess antimicrobial activity in biological samples, leading to variable blood levels and potential toxicity in critically ill patients with altered pharmacokinetics and pharmacodynamics.
Innovation Solution
A method using flow cytometry to quantify antimicrobial levels and efficacy in biological samples by incubating samples with reference or patient-derived microbial strains and fluorophores, allowing for rapid and accurate measurement of antimicrobial activity in body fluids such as blood, urine, and cerebrospinal fluid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If HPLC or immunoassays are used for TDM, then measurement precision of antimicrobial levels is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces complex mechanical/chemical systems (HPLC chromatography columns, immunoassay reagents and equipment) with a biological system based on microbial susceptibility testing. The microbial cells act as biological sensors that naturally respond to antimicrobial presence, eliminating the need for complex instrumentation while maintaining measurement capability through flow cytometric detection of cellular responses.
Solution Approach 2:
The invention uses microbial cells as proxies or biological indicators to detect antimicrobial activity. Instead of directly measuring chemical concentrations with complex instruments, the method uses living microorganisms whose physiological responses (membrane potential changes, metabolic activity) serve as indirect but reliable indicators of antimicrobial presence and efficacy, simplifying the overall measurement system.
2Measurement precision
If HPLC or immunoassays are used for TDM, then measurement precision is improved, but cost increases significantly
Solution Approach 1:
The patent employs disposable microbial cells and simple flow cytometry buffers instead of expensive, proprietary HPLC columns, immunoassay kits, and specialized reagents. The microbial suspensions can be prepared from standard culture collections or patient isolates, and the flow cytometry analysis uses readily available fluorescent dyes and standard instrumentation, dramatically reducing per-test costs while maintaining clinical utility.
Solution Approach 2:
The microbial cells perform the analytical function themselves by naturally responding to antimicrobial exposure through changes in their physiological state. This self-detection mechanism eliminates the need for expensive external detection systems, complex sample preparation protocols, and specialized trained personnel required by HPLC and immunoassay methods, making the test cheaper and easier to perform in routine clinical laboratories.
3Quantity of substance
If chemical determination methods are used, then antimicrobial concentration is measured, but antimicrobial activity assessment is lost
Solution Approach 1:
The patent creates a multi-functional assay where the same microbial susceptibility testing system simultaneously provides both quantitative antimicrobial concentration data and qualitative activity assessment. The flow cytometric measurement of cellular responses (membrane potential, viability) to antimicrobial exposure delivers information about both how much drug is present and how actively it is functioning against microorganisms, including detection of inactivation by bacterial enzymes or host factors.
Solution Approach 2:
The invention transitions from measuring a single parameter (chemical concentration) to measuring multiple physiological parameters of microbial cells (membrane potential, metabolic activity, viability) in response to antimicrobial exposure. These parameter changes in the microbial cells provide comprehensive information about both the presence and functional activity of the antimicrobial, capturing effects that chemical methods cannot detect.
4Loss of time
If rapid TDM is needed for critically ill patients, then treatment response time is improved, but measurement precision may be compromised
Solution Approach 1:
The patent uses pre-prepared microbial suspensions from standard culture collections or previously isolated patient strains that are ready for immediate testing. The flow cytometry instrumentation is pre-configured with appropriate fluorescent dyes and analysis protocols. This preliminary preparation eliminates time-consuming steps like column calibration, reagent preparation, and method validation, enabling rapid patient sample analysis without sacrificing measurement accuracy through the robust, standardized assay protocol.
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
Enables quick and personalized antimicrobial dosing adjustments, reducing toxicity and improving treatment efficacy by measuring both antimicrobial levels and activity, particularly beneficial for critically ill patients with renal or hepatic dysfunction.
Implementation Method 1
incubating the biological sample with a reference microbial strain and a fluorophore for detecting cell lesion; measuring a first signal of fluorescent intensity in the incubated biological sample using flow cytometry
Data Source
AI summary
Disclosed herein are methods and compositions for antimicrobial quantification and functional measurement. In one aspect, a method for quantifying antimicrobial comprises: obtaining a biological sample from a patient receiving an antimicrobial; incubating the biological sample with a reference microbial strain and a fluorophore for detecting cell lesion; measuring a first signal of fluorescent intensity in the incubated biological sample using flow cytometry; and comparing the first signal to a calibrating curve previously generated for the antimicrobial, thereby quantifying the antimicrobial present in the biological sample.