利用MALDI-TOF MS特异质量峰对耐碳青霉烯类肺炎克雷伯菌同源性的快速分型

目的利用基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)筛选耐碳青霉烯类肺炎克雷伯菌(CRKP)的特异质量峰,并根据特异质量峰对CRKP进行快速同源性分析。方法选取某院微生物实验室已进行多位点序列分型(MLST)的CRKP 76株,52株用于方法的建立,24株用于方法的验证。设置5个不同的特异峰挑选标准,按照不同的标准筛选各ST型特异质量峰,依据筛选的特异质量峰对CRKP进行分型,将与MLST结果符合率最高的标准确定为最佳标准。依据最佳标准筛选出的特异峰对24株CRKP进行分型,验证特异峰质量分型方法的准确性,并与质谱仪软件中的主成分分析(PCA)和核心图谱(MSP)聚类分析进行比较。结果按照标准2[(1)信噪比(S/N)≥4,(2)S/N比值≥1.5,(3)变异系数(CV)≤40%],52株CRKP中共筛选出45个特异质量峰,利用特异质量峰对29株CRKP进行分型,与MLST符合率最高,达82.8%,确定为最佳标准。按照此标准筛选出的特异质量峰对另外24株CRKP进行分型,与MLST符合率达83.3%。而PCA聚类分析与MLST的符合率仅为66.7%,MSP聚类分析与MLST一致性较差,没有明显符合ST型的分组趋势。结论利用MALDI-TOF MS筛选出不同ST型别CRKP的特异质量峰,可用于CRKP的快速同源性分析,为暴发流行的监测和医院感染的控制提供依据。

Rapid typing of homology of carbapenem-resistant Klebsiella pneumoniae based on specific mass peak of MALDI-TOF MS

Objective To screen specific mass peaks(SMP) of carbapenem-resistant Klebsiella pneumoniae (CRKP) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), and perform rapid homology analysis on CRKP based on SMP. Methods 76 strains of CRKP with multilocus sequence typing (MLST) were selected from a microbiology laboratory of a hospital, 52 strains were for establishment of method and 24 strains were for validation of method. Five different criteria for selecting SMP of CRKP were set, SMP of different ST-type were screened according to different criteria, CRKP was typed based on screened SMP, criterion with the highest coincidence rate of MLST results was determined as the best criterion. Twenty-four CRKP strains were typed according to the specific peaks screened through best criteria, accuracy of SMP typing method was verified, and was compared with principal component analysis (PCA) and main spectra profile(MSP) cluster analysis in mass spectrometer software. Results According to standard 2 (1signal-to-noise ratio[S/N] ≥ 4, 2S/N ratio ≥ 1.5, 3coefficient of variability[CV ≤ 40%]), 45 SMP were selected from 52 strains of CRKP strains, 29 strains of CRKP were typed by SMP, with the highest coincidence rate (82.8%) with MLST, which was determined as the best criterion. Another 24 CRKP strains were typed according to SMP screened based on this criterion, and the coincidence rate with MLST was 83.3%. The coincidence rate between PCA cluster analysis and MLST was only 66.7%, consistency between MSP clustering analysis and MLST was poor, and it didn't conform to the grouping trend of ST typing. Conclusion MALDI-TOF MS can select SMP of CRKP of different ST, which can be used for rapid homology analysis on CRKP, provide basis for surveillance and control of outbreak of healthcare-associated infection.