Urine LAM Detection for NTM Diagnosis via GC/MS
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Solution Overview
Problem
Current methods for detecting nontuberculous mycobacterial (NTM) infections in cystic fibrosis patients are inadequate due to the lack of sensitive and specific markers, with culture-based methods being slow, costly, and difficult to perform, especially in children and non-sputum producers, and urine LAM tests having low sensitivity and high specificity.
Innovation Solution
A novel method involving the detection of lipoarabinomannan (LAM) or its derivatives in urine samples using gas chromatography-mass spectrometry (GC/MS) after purification by hydrophobic interaction chromatography, with the use of internal standards and specific derivatization techniques to distinguish D-arabinose and tuberculostearic acid, allowing for the identification of NTM infections and potentially replacing sputum cultures as a screening tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If culture-based methods are used for NTM detection, then diagnostic accuracy is improved, but detection time increases significantly (up to 8 weeks)
Solution Approach 1:
The patent applies preliminary action by performing a rapid preliminary detection of LAM in urine samples using GC/MS before proceeding to confirmatory culture methods. This allows clinicians to quickly identify patients who are likely to have NTM infection and prioritize them for further diagnostic workup, while avoiding unnecessary prolonged testing in patients who are unlikely to be infected.
Solution Approach 2:
The diagnostic process is segmented into two distinct stages: (1) a rapid screening phase using LAM detection in urine samples with GC/MS that provides results within hours, and (2) a confirmatory phase using traditional culture methods that take up to 8 weeks. This segmentation allows the system to leverage the speed of molecular detection while maintaining the diagnostic gold standard of culture when needed.
2Measurement precision
If sputum culture is performed, then diagnostic specificity is improved, but ease of operation deteriorates due to difficulty in obtaining samples from children and non-sputum producers
Solution Approach 1:
The patent uses urine LAM detection as an intermediary test that bridges the gap between the need for specific diagnosis and the difficulty of obtaining sputum samples. Urine is easily collectable from all patients including children and non-sputum producers, and LAM detection in urine provides diagnostic information that correlates with NTM infection status without requiring invasive or difficult sample collection procedures.
Solution Approach 2:
The patent replaces the mechanical process of sputum expectoration and processing with a biochemical detection method. Instead of requiring patients to produce and process sputum samples through mechanical means (expectoration, centrifugation, decontamination), the method uses biochemical detection of LAM in easily collectable urine samples, substituting a complex mechanical sample collection system with a simpler biochemical assay.
3Ease of operation
If urine LAM tests are used, then ease of operation is improved (non-invasive sampling), but sensitivity decreases
Solution Approach 1:
The patent replaces less sensitive immunological detection methods with gas chromatography-mass spectrometry (GC/MS) for LAM detection in urine. GC/MS provides significantly enhanced sensitivity and specificity compared to traditional immunological assays, allowing the method to maintain the ease of non-invasive urine sampling while overcoming the sensitivity limitation of previous urine-based tests.
Solution Approach 2:
The patent changes the detection parameters by using GC/MS with specific derivatization techniques and internal standards to detect LAM in urine. This represents a fundamental change in the detection methodology from immunological assays to mass spectrometric analysis, which operates at different sensitivity thresholds and provides more precise quantification of LAM levels in urine samples.
4Reliability
If traditional culture methods are used, then diagnostic reliability is improved, but productivity decreases due to slow growth rates
Solution Approach 1:
The patent segments the diagnostic workflow into a high-throughput screening component (LAM detection in urine using GC/MS) that can process many samples rapidly, and a low-throughput confirmatory component (traditional culture) that maintains diagnostic reliability but is performed only on selected cases. This segmentation allows the system to achieve high overall productivity while preserving diagnostic reliability through selective use of culture methods.
Solution Approach 2:
The patent performs preliminary LAM detection in urine samples using GC/MS before proceeding to confirmatory culture methods. This preliminary action identifies patients who are likely to have NTM infection, allowing clinicians to prioritize these cases for further diagnostic workup and treatment planning, while avoiding unnecessary prolonged testing in patients who are unlikely to be infected, thereby increasing overall system productivity.
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 method provides a non-invasive, cost-effective, and sensitive detection of NTM infections, reducing the need for frequent sputum sampling and potentially replacing traditional culture-based methods, with a two-step screening strategy that can identify patients who do not require further NTM testing for at least six months to a year.
Implementation Method 1
purification by hydrophobic interaction chromatography
Implementation Method 2
gas chromatography-mass spectrometry (GC/MS)
Implementation Method 3
gas chromatography-mass spectrometry (GC/MS)
Implementation Method 4
specific derivatization techniques to distinguish D-arabinose and tuberculostearic acid
Data Source
AI summary
Methods for detecting a mycobacterial infection in a patient are disclosed. These methods include the step of detecting lipoarabinomannan (LAM) and/or derivatives thereof in a biological sample from the patient. Methods for diagnosing disease, including nontuberculous mycobacterial infection (NTM), and kits for the described methods are also provided.