Christner Martin, Trusch Maria, Rohde Holger, Kwiatkowski Marcel, Schlüter Hartmut, Wolters Manuel, Aepfelbacher Martin, Hentschke Moritz
Department of Medical Microbiology, Virology and Hygiene, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Institute of Organic Chemistry, Mass Spectrometry Facility, University of Hamburg, Hamburg, Germany.
PLoS One. 2014 Jul 8;9(7):e101924. doi: 10.1371/journal.pone.0101924. eCollection 2014.
In 2011 northern Germany experienced a large outbreak of Shiga-Toxigenic Escherichia coli O104:H4. The large amount of samples sent to microbiology laboratories for epidemiological assessment highlighted the importance of fast and inexpensive typing procedures. We have therefore evaluated the applicability of a MALDI-TOF mass spectrometry based strategy for outbreak strain identification.
Specific peaks in the outbreak strain's spectrum were identified by comparative analysis of archived pre-outbreak spectra that had been acquired for routine species-level identification. Proteins underlying these discriminatory peaks were identified by liquid chromatography tandem mass spectrometry and validated against publicly available databases. The resulting typing scheme was evaluated against PCR genotyping with 294 E. coli isolates from clinical samples collected during the outbreak.
Comparative spectrum analysis revealed two characteristic peaks at m/z 6711 and m/z 10883. The underlying proteins were found to be of low prevalence among genome sequenced E. coli strains. Marker peak detection correctly classified 292 of 293 study isolates, including all 104 outbreak isolates.
MALDI-TOF mass spectrometry allowed for reliable outbreak strain identification during a large outbreak of Shiga-Toxigenic E. coli. The applied typing strategy could probably be adapted to other typing tasks and might facilitate epidemiological surveys as part of the routine pathogen identification workflow.
2011年德国北部爆发了大规模的产志贺毒素大肠杆菌O104:H4疫情。大量样本被送往微生物实验室进行流行病学评估，这凸显了快速且低成本分型程序的重要性。因此，我们评估了基于基质辅助激光解吸电离飞行时间质谱（MALDI-TOF）的策略在疫情菌株鉴定中的适用性。
通过对为常规菌种水平鉴定而采集的疫情爆发前存档光谱进行比较分析，确定疫情菌株光谱中的特定峰。通过液相色谱串联质谱鉴定这些鉴别峰所对应的蛋白质，并针对公开可用数据库进行验证。将所得分型方案与从疫情期间收集的临床样本中分离出的294株大肠杆菌进行PCR基因分型评估。
比较光谱分析显示在m/z 6711和m/z 10883处有两个特征峰。发现其对应的蛋白质在基因组测序的大肠杆菌菌株中普遍存在率较低。标记峰检测正确分类了293株研究菌株中的292株，包括所有104株疫情菌株。
MALDI-TOF质谱能够在大规模产志贺毒素大肠杆菌疫情期间可靠地鉴定疫情菌株。所应用的分型策略可能适用于其他分型任务，并可能作为常规病原体鉴定工作流程的一部分促进流行病学调查。
