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

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.