质谱对甲氧西林耐药和甲氧西林敏感金黄色葡萄球菌的鉴定价值

Value of Mass Spectrometry in Identification of Methicillin-Resistant and Methicillin-Sensitive Staphylococcus Aureus

为了分析基质辅助激光解析电离飞行时间质谱(matrix-Assisted laser desorption Ionization-time of flight mass spectrometry,MALDI-TOF-MS)对耐甲氧西林金黄色葡萄球菌(methicillin-resistant Staphylococcus aureus,MRSA)和甲氧西林敏感金黄色葡萄球菌(methicillin-sensitive Staphylococcus aureus,MSSA)的鉴定价值。选择2017年3月—2018年2月山西医科大学公共卫生学院接受治疗的患者1 153例,检测患者体液、血液及坏死性组织样本,分离出致病菌后,利用全自动微生物鉴定及药敏分析系统最终确定为金黄色葡萄球菌。对细菌进行质谱仪鉴定分析,联合ClinPro Tools软件建立模型分析MRSA及MSSA质谱图差异,找到特征峰,并验证质谱图特征峰对区分MRSA和MSSA的鉴定价值。结果显示共分离出MRSA及MSSA各58株、42株。随机选取26株MRSA和19株MSSA,找到MRSA主要特征峰共2个,即特征峰1 2 305.6 Da和特征峰2 3 007.3 Da。利用其他32株MRSA和23株MSSA对此模型进行验证,以MIC法作为金标准评价质谱特征峰区分金黄色葡萄球菌的价值。特征峰1灵敏度71.9%,特异度82.6%;特征峰2灵敏度68.8%,特异度87%;将两点联合起来,灵敏度为90.6%,特异度为73.9%。说明质谱对MRSA和MSSA的鉴定价值良好,有助于判断金黄色葡萄球菌耐药表型。

To analyze methicillin-resistant Staphylococcus aureus(MRSA)by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry(MALDI-TOF-MS)and the identification value of methicillin-sensitive Staphylococcus aureus(MSSA).From March 2017 to February 2018,the study period was selected.1 153 patients who were treated in our hospital during this period were selected.The samples of body fluid,blood and necrotic tissue were detected,and the pathogens were isolated and utilized.The automated microbial identification and drug susceptibility analysis system was finally identified as S.aureus.After mass spectrometry identification of the bacteria,the ClinPro Tools software was used to establish a model to analyze the difference between the MRSA and MSSA mass spectra,find the characteristic peaks,and verify the identification value of the characteristic peaks of the spectrum to distinguish MRSA and MSSA.A total of 58 strains and 42 strains of MRSA and MSSA were isolated.26 strains of MRSA and 19 strains of MSSA were randomly selected.Two major peaks of MRSA were found,namely,characteristic peak-2305.6Da and characteristic peak 23007.3Da.This model was validated using 32 strains of MRSA and 23 strains of MSSA,and the value of the characteristic peak of the mass spectrum was evaluated by the MIC method as a gold standard to distinguish the value of Staphylococcus aureus.The characteristic peak-sensitivity is 71.9%,the specificity is 82.6%;the characteristic peak two sensitivity is 68.8%,and the specificity is 87%;when the two points are combined,the sensitivity is 90.6%,and the specificity is 73.9%.Mass spectrometry has good value for the identification of MRSA and MSSA,which is helpful to judge the resistant phenotype of Staphylococcus aureus.