采用基质辅助激光解析电离飞行时间质谱快速检测产KPC大肠埃希菌ST131和ST405分型的研究

Matrix-assisted laser desorption ionization-time of flight mass spectrometry for rapid typing of KPC-producing Escherichia coli ST131 and ST405

目的采用基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)快速检测产KPC大肠埃希菌ST131、ST405,并对该方法的可行性进行评价。方法收集浙江省人民医院临床分离46株大肠埃希菌,扩增blaKPC耐药基因,采用多位点序列分型方法(MLST)进行分型。MALDI-TOF MS对大肠埃希菌进行鉴定并对不同克隆的峰图进行主成分分析和算法统计,获得分型区分的特征峰。结果 46株KPC型大肠埃希菌均携带KPC-2耐药基因,MLST方法检测到2种ST型,分别为ST131和ST405。主成分分析图显示ST131和ST405可分为2簇,其中2株ST131和3株ST405分类错误。ClinProTools软件4种算法结果基本相似,方法特异度和灵敏度分别为93.27%和97.92%。用于区分ST131和ST405的特征峰主要为8 331.84、4 166.44、4 860.21和2 783.66 Da。这4个峰区分具有统计学意义,有较高准确性。结论采用MALDI-TOF MS可快速区分产KPC大肠埃希菌ST131和ST405,具有操作简单、耗时短、区分灵敏度和特异度高以及成本低等优点,能用于大肠埃希菌克隆分型研究。

Objective To rapidly identify and detect KPC-producing Escherichia coli ST 131 and ST405 groups by matrix-assisted laser desorption ionization - time of flight mass spectrometry （MALDI-TOF MS） method. Methods Forty-six E.coli isolates were collected from Zhejiang Provincial People＇s Hospital. The blar^c gene was amplified and multilocus sequence typing （MLST） was performed to analyze the molecular typing of these strains. All the strains were identified by using MALDI-TOF MS method. The resulting mass spectra were analyzed by principal component analysis and algorithm statistics to obtain the characteristic peaks. Results All the 46 E. coli isolates carried KPC-2 resistant gene. MLST showed two clonal groups ofE. coli, ST131 and ST405. Principal component analysis diagram indicated the ST131 and ST405 groups were divided into two clusters, but two ST 131 and three ST405 isolates were misclassified. The four standard algorithms in ClinProTools provided similar results in differentiatingST 131 from ST405 isolates. The sensitivity and specificity were 93.27 % and 97.92 %, respectively. Four main characteristic peaks were 8 331.84, 4 166.44, 4 860.21 and 2 783.66 Da, which had statistical significance and high accuracy in differentiating the strains. Conclusions MALDI-TOF MS method has shown good performance in differentiating ST131 from ST405 clonal groups. It is simple to operate at low cost and short time with high sensitivity and specificity.