Journal of mass spectrometry and advances in the clinical lab · ·Added 11 Nov 2026

Rapid Biotyping Discrimination of Methicillin-Susceptible and -Resistant Staphylococcus aureus Using Flow Injection Analysis-Ion Mobility-Mass Spectrometry.

Muhammad Ramzan, Michael W Christopher, Autumn S Dove, Kwangcheol C Jeong, Daniel M Czyz, Syed Ghulam Musharraf, Timothy J Garrett

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Abstract

INTRODUCTION: Antimicrobial resistance is a leading contributor to global mortality. Among the most concerning pathogens is Staphylococcus aureus, a gram-positive bacterium capable of causing severe infections. Particularly problematic is methicillin-resistant S. aureus (MRSA), which exhibits extensive resistance to antibiotics. Rapid differentiation between resistant and susceptible strains is essential for early and accurate intervention, enabling timely administration of appropriate antibiotics. However, conventional diagnostic methods remain slow, labor-intensive, and costly. METHODS: In this study, we developed a method using flow injection analysis-ion mobility-high-resolution mass spectrometry for the rapid discrimination of MRSA from its susceptible counterpart, methicillin-susceptible S. aureus (MSSA). The total instrument run time is 2 min, and samples can be analyzed after 6 h of incubation. RESULTS: MRSA was distinguished from MSSA based on the detection of three peptide peaks at m/z 733.791, 763.176, and 769.129, proposed as marker peaks for differentiating MRSA from MSSA. These peptide peaks were identified as phenol-soluble modulins (PSMα1, PSMα2, and PSMα4) using HRMS by applying de novo sequencing from HRMS/MS data. CONCLUSION: Our study may facilitate the rapid detection and discrimination of S. aureus strains, potentially enabling timely intervention and therapeutic strategies for affected patients. Antimicrobial resistance is a major health threat, and methicillin-resistant Staphylococcus aureus (MRSA), a hard-to-treat form of Staphylococcus aureus, is a key concern. Standard tests to determine whether a strain is drug-resistant are slow and expensive. This study introduces a rapid lab method that, after only 6 h of growth and a 2 min measurement, identifies three peptide markers unique to MRSA. This could allow much faster detection of resistant strains and quicker, more targeted treatment for patients.

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