MALDI-TOF MS检测在粪肠球菌中的应用效果分析

Application of MALDI-TOF MS in detection of Enterococcus faecalis

目的:使用基质辅助激光解吸电离飞行时间质谱仪(MALDI-TOF MS)鉴别耐利奈唑胺粪肠球菌(LRE)和利奈唑胺敏感粪肠球菌(LSE),探讨MALDI-TOF MS检测在粪肠球菌中的应用效果,并对LRE进行流行病学相关性分析。方法:选取2020年1月—2022年3月临床分离出的78株粪肠球菌菌株,其中LRE 38株、LSE 40株。采用MIC药敏方法确定利奈唑胺耐药情况,使用MALDI-TOF MS对菌株进行鉴定并采集图谱,使用ClinPro Tools软件对质谱峰进行分析,选取其中的18株LRE和20株LSE进行模型的建立,并用剩余20株LRE和20株LSE进行模型的验证。结果:使用MALDI-TOF MS遗传算法建立的最佳模型进行验证,敏感性为85.00%,特异性为90.00%,阳性预测值为89.47%,阴性预测值为85.71%。LRE的38菌株中携带optrA基因的菌株30株,占78.94%(30/38),cfr基因阳性的6株,占15.78%(6/38),出现L4突变的有4株,出现L3突变的有1株。使用脉冲场凝胶电泳技术(pulsed-field gel electrophoresis,PFGE)对38株LRE进行分析,可得Ⅰa型有7株,Ⅰb型有5株,Ⅱa为25株,Ⅱb为1株,并对38株LRE菌株使用MALDI-TOF MS进行同源性分析,结果与PFGE结果一致。结论:LRE主要耐药机制是optrA基因所致,MALDI-TOF MS能够快速、准确的鉴定出耐利奈唑胺的粪肠球菌,有利于指导临床合理用药以及调查社区和院内感染传播的危险因素和传播途径,为院感防控提供依据。

Objective To identify Linezolid Resistant Enterococcus Faecalis(LRE)and Linezolid Sensitive Enterococcus faecalis(LSE)by matrix assisted laser desorpsion/ionization time-of-flight mass spectrometry(MALDI-TOF MS),discuss the application effect of MALDI-TOF MS in detection of enterococcus faecalis,and analyze the epidemiological correlation of LRE.Methods 78 clinical isolates of enterococcus faecalis were selected,including 38 strains of LRE and 40 strains of LSE.MIC drug sensitivity method was used to determine the resistance to linezolid.MALDI-TOF MS was used to identify the strain and collect the spectrum.ClinPro Tools software was used to analyze the mass spectrum peak.Among them,18 LREs and 20 LSEs were selected for model establishment,and the remaining 20 LREs and 20 LSEs were used for model validation.Results The sensitivity,specificity,positive predictive value and negative predictive value of the best model established by MALDI-TOF MS genetic algorithm were 85.00%,90.00%,89.47%and 85.71%respectively.Among 38 strains of LRE,30 strains carried optrA gene,accounting for 78.94%(30/38),6 strains were positive for cfr gene,accounting for 15.78%(6/38),4 strains had L4 mutation,and 1 strain had L3 mutation.38 strains of LRE were analyzed by pulsed field gel electrophoresis(PFGE).Seven strains of type Ia,five strains of type Ib,25 strains of type IIa,and one strain of type IIb were obtained.Conclusion The main drug resistance mechanism of LRE is caused by optrA gene.MALDI-TOF MS can quickly and accurately identify linezolid resistant enterococcus faecalis,which is helpful to guide clinical rational drug use,investigate the risk factors and transmission routes of infection transmission in communities and hospitals,and provide basis for hospital infection prevention and control.