国产MALDI-TOF MS系统Smart MS 5020对临床微生物的鉴定性能评估

Evaluation for performance of domestic MALDI-TOF MS Smart MS 5020 in identification of clinical microorganisms

目的评估珠海迪尔Smart MS 5020型基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)系统及其2630种数据库(以下简称Smart MS 5020系统)对临床微生物的鉴定能力。方法共纳入2016—2020年浙江大学医学院附属第二医院留存的临床分离菌株913株,覆盖18个属52个种或复合群。采用直接涂抹法进行鉴定,比对仪器为德国布鲁克Biotyper MS系统及其DB2969数据库(以下简称Biotyper MS),对于两台质谱仪不一致的鉴定结果,采用16S rRNA扩增测序作为判定的金标准。针对复合群(鲍曼不动杆菌复合群、阴沟肠杆菌复合群以及肺炎克雷伯菌复合群),采用二代测序的鉴定结果作为金标准,统计学方法采用卡方检验。选取13株室内质控菌株作为重复性评估的检测样本,每株菌在Smart MS 5020系统上平行检测3次,判断其鉴定结果的一致性。结果对913株临床菌株,Biotyper MS系统种水平鉴定准确率为100%(913/913,95%CI:99.48%~99.58%),Smart MS 5020系统种水平鉴定准确率为99.78%(911/913,95%CI:99.12%~99.20%),2株表皮葡萄球菌鉴定为柯氏葡萄球菌;在临床微生物的鉴定能力方面,2种方法差异无统计学意义(P>0.05)。重复性评估结果显示,Smart MS 5020系统对13株室内质控菌株的鉴定结果完全一致。结论Smart MS 5020系统对临床常见微生物有很好的鉴定能力,包括复合群的鉴定能准确鉴定到复合群,对一些难区分菌如嗜血杆菌、链球菌等均能准确鉴定,但对复合群内具体种的细分能力有限,需要结合分子生物学、血清学或其他补充实验来准确鉴定。

Objective To evaluate the performance of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS)Smart MS 5020 system with 2630 database(Smart MS 5020)in identification of clinical microorganisms.Methods A total of 913 microorganisms of 18 genera,52 species/species complex isolated from The Second Affiliated Hospital of Zhejiang University,School of Medicine were included from the year 2016 to 2020.Bacterial identification was performed with a direct smear method.The results of Smart MS 5020 system were parallelly compared with those of German Bruker Biotyper MS DB2969 database(Biotyper MS system).The 16S rRNA sequencing was used as the reference method if either the MALDI-TOF MS system could not identify the isolates or discrepant results were showed.For species complexes(Acinetobacter baumannii complex,Enterobacter cloacae complex and Klebsiella pneumoniae complex),the identification results of next-generation sequencing were used as the gold standard.Pearson chi-square(χ2)test was used to calculate the statistical significance.Thirteen strains of quality control were selected as the test samples for assessment of repeatability,and each strain was tested thrice in parallel on the Smart MS 5020 system to evaluate the consistency of the identification results.Results For the 913 clinical isolates,the accuracy in species level of Biotyper MS system was 100%(913/913,95%CI:99.48%to 99.58%),and that of Smart MS 5020 system was 99.78%(911/913,95%CI:99.12%to 99.20%).Two Staphylococcus epidermidis strains were misidentified as Staphylococcus korskii.No significant difference between the results of the two MS systems was found in the identification ability of clinical microorganisms(P>0.05).The repeatability evaluation revealed that the identification results of the 13 quality control strains by Smart MS 5020 system were completely consistent.Conclusion The performance of Smart MS 5020 system was comparable to that of Biotyper MS for the identification of clinical microorganisms,including the species complexes and some indistinguishable bacteria,such as Haemophilus sp.and Streptococcus sp.However,the identifying ability for subdivided complexes of specific species within species complexes is challenging,so 16S rRNA sequencing is still needed combining serological or other supplementary experiments to confirm.