Accurate differentiation of novel Staphylococcus argenteus from Staphylococcus aureus using MALDI-TOF MS

Aim: We evaluated a Staphylococcus argenteus-specific diagnostic profile of matrix-assisted laser desorption/ionization time-of-flight mass spectrometer for accurate identification of this novel bacterium. Materials & methods: Staphylococcus argenteus was identified based on negative crtM gene and presence of specific sequence types. A classification model was generated by cluster analysis of matrix-assisted laser desorption/ionization time-of-flight mass spectrometer results and ClinProTools software for 25 S. argenteus and 25 methicillin-susceptible S. aureus (MSSA). The performance of the classification model was validated against 72 S. argenteus and 72 MSSA isolates. Results: With cluster analysis and classification model, differentiation of 72 S. argenteus from 72 MSSA had 100.0% accuracy by chemical extraction method and 87.5% sensitivity and 100.0% specificity by direct smear method. Conclusion: The classification model could accurately differentiate S. argenteus from MSSA.