MALDI-TOF mass spectrometry following short incubation on a solid medium is a valuable tool for rapid pathogen identification from positive blood cultures
MALDI-TOF mass spectrometry following short incubation on a solid medium is a valuable tool for rapid pathogen identification from positive blood cultures
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DOI：
10.1016/j.ijmm.2015.04.004
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发表时间：
2015-06-01
影响因子：
4.1
通讯作者：
Gatermann, Soeren
中科院分区：
文献类型：
--
作者：
Kohlmann, Rebekka;Hoffmann, Alexander;Gatermann, Soeren
引言：快速鉴定致病微生物是血流感染适当抗菌治疗的关键因素。然而，阳性血培养物的传统分析需要在通过例如基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）鉴定病原体之前传代培养至少16-24小时，使得能够直接MALDI-TOF MS的样品制备程序（即没有预先传代培养）与额外的努力和成本相关。因此，我们集成了一个替代的MALDI-TOF MS方法在诊断常规使用一个短的孵育固体medium.Materials和方法：阳性血培养物常规平板上的巧克力琼脂板和孵育4小时（37摄氏度，5%CO2）。随后，使用Microflex LT仪器（Bruker Daltonics）和直接涂片法对每个样品进行一次MALDI-TOF MS。为了在物种水平上成功鉴定细菌，如制造商所提议的（>= 2.0）和以修改的形式（对于涉及革兰氏阳性球菌的MALDI-TOF MS结果，>= 1.5;对于涉及革兰氏阳性球菌以外的细菌的MALDI-TOF MS结果，>= 1.7）使用评分截止值。进一步的数据分析还包括对MALDI-TOF MS结果的临床影响的评估。结果：应用修改后的评分截止值，我们的方法导致了69.5%的总体正确物种鉴定与3.4%的错误鉴定（原临界值：分别为49.2%和1.8%）;对革兰阳性球菌的正确识别率为68.4%对金黄色葡萄球菌和肠球菌的正确鉴定率为100%，对β-溶血性链球菌的正确鉴定率为80%，对革兰阴性菌的正确鉴定率为97.6%。在多种微生物血培养中，72.7%的病原体被正确识别。革兰氏阳性杆菌和酵母菌的结果不可靠。该方法易于在诊断程序中实现。在可用的临床数据和成功的病原体鉴定的情况下，在51.1%，我们的方法允许优化的治疗recommendation.Conclusion：MALDI-TOF MS后4小时的预培养是一个有价值的工具，用于快速病原体鉴定阳性血培养，允许轻松集成在诊断常规和机会，相当早的治疗适应。(C)2015爱思唯尔有限公司All rights reserved.
Introduction: Rapid identification of the causative microorganism is a key element in appropriate antimicrobial therapy of bloodstream infections. Whereas traditional analysis of positive blood cultures requires subculture over at least 16-24 h prior to pathogen identification by, e.g. matrix-assisted laser-desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), sample preparation procedures enabling direct MALDI-TOF MS, i.e. without preceding subculture, are associated with additional effort and costs. Hence, we integrated an alternative MALDI-TOF MS approach in diagnostic routine using a short incubation on a solid medium.Materials and methods: Positive blood cultures were routinely plated on chocolate agar plates and incubated for 4h (37 degrees C, 5% CO2). Subsequently, MALDI-TOF MS using a Microflex LT instrument (Bruker Daltonics) and direct smear method was performed once per sample. For successful identification of bacteria at species level, score cut-off values were used as proposed by the manufacturer (>= 2.0) and in a modified form (>= 1.5 for MALDI-TOF MS results referring to Gram-positive cocci and >= 1.7 for MALDI-TOF MS results referring to bacteria other than Gram-positive cocci). Further data analysis also included an assessment of the clinical impact of the MALDI-TOF MS result.Results: Applying the modified score cut-off values, our approach led to an overall correct species identification in 69.5% with misidentification in 3.4% (original cut-offs: 49.2% and 1.8%, respectively); for Gram-positive cocci, correct identification in 68.4% (100% for Staphylococcus aureus and enterococci, 80% for beta-hemolytic streptococci), for Gram-negative bacteria, correct identification in 97.6%. In polymicrobial blood cultures, in 72.7% one of the pathogens was correctly identified. Results were not reliable for Gram-positive rods and yeasts. The approach was easy to implement in diagnostic routine. In cases with available clinical data and successful pathogen identification, in 51.1% our approach allowed an optimized treatment recommendation.Conclusion: MALDI-TOF MS following 4 h pre-culture is a valuable tool for rapid pathogen identification from positive blood cultures, allowing easy integration in diagnostic routine and the opportunity of considerably earlier treatment adaptation. (C) 2015 Elsevier GmbH. All rights reserved.