2B-O1-1050 PDF
Rapid identification of microorganisms by mass spectrometry
Methicillin-resistant Staphylococcus aureus (MRSA) is one of the major pathogens responsible for nosocomial infection. The presence of MRSA in a hospital is detrimental to patients and to hospital management. Thus, rapid identification of MRSA is needed. Here, we report a prospective study of rapid discrimination of MSSA from MRSA using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) and support vector machine (SVM) analysis in 305 clinical isolates of S. aureus. The predictive model was trained using 100 S. aureus isolates (50 MSSA and 50 MRSA). The identification rates were 90.0% for MSSA and 87.5% for MRSA in a 10-fold cross-validation SVM. In blind test sets, 205 S. aureus isolates (95 MSSA and 110 MRSA) were correctly classified, with identification rates of 95.8% for MSSA and 81.8% for MRSA. The method proposed in this study using a predictive model enables detection in one colony in 5 minutes, and thus is useful at clinical sites at which rapid discrimination of MRSA from MSSA is required.