Rapid identification of methicillin-resistant Staphylococcus aureus and methicillin-sensitive Staphylo-coccus aureus strains by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry / 中华微生物学和免疫学杂志

ABSTRACT

Objective To evaluate the capability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry ( MALDI-TOF MS) for rapid identification of methicillin-resistant Staphylo-coccus aureus (MRSA) and methicillin-sensitive Staphylococcus aureus (MSSA) strains.Methods Twenty-five MRSA and thirty MSSA isolates were collected from the Second Affiliated Hospital of Zhejiang University School of Medicine as the experiment group .Twelve MRSA and twenty-two MSSA clinical strains were isola-ted as the control .All strains were identified by MALDI-TOF MS and the results were further analyzed by ClinProTools 3.0 software.Results Four algorithms including support vector machine (SVM), genetic al-gorithm ( GA) , supervised neural network ( SNN) and quick classifier ( QC) showed similar results in dis-tinguishing MRSA from MSSA isolates .The sensitivity of GA was 100 .0%and the sensitivities of other algo-rithms were all greater than 95.0%.The specificities of GA, SVM and QC were all greater than 90.0%. The areas under the receiver operating characteristic ( ROC) curves of four characteristic peaks at mass-to-charge ratios (m/z) of 3279, 6485, 6555 and 3299 m/z were all greater than 0.9.The virtual gel view showed that the bands generated by MSSA isolates at 3279 , 6485 and 6555 m/z were obviously deeper in color than those generated by MRSA isolates .However , the bands of MSSA isolates at 3299 m/z were appar-ently lighter in color than those of MRSA isolates .83.3%of MRSA and 90.0%of MSSA isolates from the control group were correctly identified by the GA model .Conclusion MALDI-TOF MS could rapidly and accurately identify MRSA from MSSA isolates under the strictly controlled experimental conditions with the advantages of less time-consuming, high sensitivity and high specificity .The accurate identification of MRSA from MSSA isolates could be applied for the prevention and treatment of MRSA infection .