PSM-mec Peptide Biomarker for MRSA Detection

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Solution Overview

Problem

Current methods for identifying methicillin-resistant Staphylococcus aureus (MRSA) using mass spectrometry face challenges in accurately differentiating MRSA from methicillin-sensitive S. aureus (MSSA) due to the low detection of resistant proteins in cell extracts, necessitating a more specific and reliable biomarker for accurate classification.

Innovation Solution

The method involves classifying bacteria as Staphylococcus aureus by mass spectrometry and determining the presence of the phenol soluble modulin peptide (PSM-mec) or its variant, specifically using a mass signal at m/z 2415, which indicates methicillin-resistant S. aureus, and further confirms the agr system status to differentiate between MRSA and MSSA.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If mass spectrometry is used to detect resistant proteins in cell extracts for MRSA identification, then the method can differentiate between MRSA and MSSA, but the detection accuracy is low due to low levels of resistant proteins in cell extracts

Engineering Contradiction:

Improvedetection accuracy of MRSAVSAvoidconcentration of resistant proteins

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The invention extracts and isolates the specific PSM-mec peptide biomarker from complex bacterial cell extracts using targeted mass spectrometry detection. By focusing on this specific peptide rather than detecting all proteins, the method overcomes the low concentration problem of resistant proteins and achieves high detection accuracy for MRSA identification

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the detection parameter from general protein detection to specific peptide mass-to-charge ratio (m/z) detection. By monitoring the specific m/z value of PSM-mec peptide, the method transforms the detection approach to achieve high sensitivity and specificity even at low peptide concentrations, resolving the contradiction between low substance quantity and measurement precision

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If general mass spectrometry methods are used for bacterial identification, then the method can identify bacterial species, but it cannot reliably differentiate MRSA from MSSA strains

Engineering Contradiction:

Improvebacterial identification capabilityVSAvoiddifferentiation accuracy of MRSA vs MSSA

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention segments the bacterial identification process into two distinct stages: first identifying the bacterial species as Staphylococcus aureus, then differentiating between MRSA and MSSA strains by detecting the specific PSM-mec peptide. This segmentation allows the method to maintain versatility for bacterial identification while achieving high reliability for MRSA differentiation

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces the PSM-mec peptide as an intermediary biomarker that links bacterial identification with resistance differentiation. This peptide serves as a specific marker that is present in MRSA strains but absent in MSSA strains, enabling reliable differentiation while maintaining the overall identification capability

Inventive Principle:

Principle #24Intermediary (Mediator)

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 provides a sensitive and specific method for identifying MRSA, enhancing the accuracy of bacterial classification and enabling early detection of nosocomial MRSA strains, thereby improving hospital hygiene by facilitating timely isolation of infected patients.

Implementation Method 1

matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI TOF MS) of intact cells is increasingly used for the identification of bacteria from patient samples

Methodology Applied

Scientific EffectMass spectrometry:

Implementation Method 2

matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI TOF MS)

Methodology Applied

Scientific EffectLaser desorption/ionization:

Data Source

PatentUS11053533B2Identification of methicillin resistant <i>Staphylococcus aureus </i>(MRSA)

Publication Date: 2021.07.06 BRUKER DALTONIK GMBH & CO KG

AI summary

The invention provides a method for identifying methicillin resistant Staphylococcus aureus (MRSA) in a bacterial sample comprising the steps: classifying bacteria in the sample as Staphylococcus aureus (SA) and determining the presence or absence of the phenol soluble modulin peptide or a variant thereof wherein the presence of the PSM-mec peptide or variant thereof indicates methicillin resistant Staphylococcus aureus. The variant is preferably the formylated version of the PSM-mec peptide having a mass to charge ratio of 2415 in a singly protonated state.