Proteomic and metabolomic profiling of methicillin-resistant Staphylococcus aureus associated with invasive vs. non-invasive infections: uncovering key biomarkers and pathogenic pathways.

INTRODUCTION

Understanding the behavioral differences between invasive and non-invasive methicillin-resistant Staphylococcus aureus (MRSA) is essential for unraveling infection mechanisms and identifying biomarkers with translational potential. This study compared the proteomic and metabolomic profiles of MRSA isolates from diverse clinical presentations to uncover distinct molecular signatures.

METHODS

Invasive isolates were obtained from blood cultures (n = 23), while non-invasive isolates were derived from superficial skin infections (n = 49) and nasal colonizers (n = 24) from screening swabs. Proteins and metabolites were simultaneously extracted using a dual-phase methanol-based protocol. Proteomic analysis was performed on the Orbitrap Exploris 480, while metabolites were characterized using a TimsTOF mass spectrometer with an Apollo II electrospray ionization source. Data-independent acquisition (DIA) was applied, with peptide assignment carried out in DIA-NN and metabolite analysis using MetaboScape® 4.0.

RESULTS

Across all isolates, 2,000 proteins and 150 metabolites were identified. Comparative analysis revealed that invasive isolates exhibited consistently higher levels of two metabolites (sphinganine and phosphoserine) and one protein (staphylococcal secretory antigen SsaA2) compared to non-invasive. In contrast, three metabolites (cytidine, benzoic acid, and guanosine) and two proteins (small ribosomal subunit protein bS20 and bifunctional autolysin) were significantly reduced in invasive isolates. These findings highlight key molecular differences underpinning invasive potential in MRSA, providing insights into candidate diagnostic and therapeutic biomarkers. These findings highlight critical biological differences between invasive and non-invasive MRSA, offering valuable insights into potential diagnostic and therapeutic biomarkers.