Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden.
Eur J Clin Microbiol Infect Dis. 2018 Jan;37(1):57-68. doi: 10.1007/s10096-017-3101-x. Epub 2017 Sep 18.
In this study we present a method using whole cell MALDI-TOF MS and VITEK MS RUO/SARAMIS as a rapid epidemiological screening tool. MRSA was used as a model organism for setting up the screening strategy. A collection of well-characterised MRSA strains representing the 19 most common Pulsed-Field Gel Electrophoresis (PFGE)-types in the region of South-West Sweden for the past 20 years was analysed with MALDI-TOF MS. A total of 111 MRSA strains were used for creating 19 PFGE-specific Superspectra using VITEK MS RUO/SARAMIS. Prior to performing the final analysis, the 19 Superspectra were combined into ten groups displaying similar peak patterns, hereafter named "MALDI-types". Two-hundred fifty-five MRSA strains were analysed to test the constructed Superspectra/MALDI-type database. Matches to the Superspectra above a threshold of 65% (corresponding to the number of matched peaks in the Superspectrum) were considered as positive assignment of a strain to a MALDI-type. The median peak matching value for correct assignment of a strain to a MALDI-type was 78% (range 65.3-100%). In total, 172 strains (67.4%) were assigned to the correct MALDI-type and only 5.5% of the strains were incorrectly assigned to another MALDI-type than the expected based on the PFGE-type of the strain. We envision this methodology as a cost-efficient step to be used as a first screening strategy in the typing scheme of MRSA isolates, to exclude epidemiological relatedness of isolates or to identify the need for further typing.
在本研究中，我们提出了一种使用全细胞 MALDI-TOF MS 和 VITEK MS RUO/SARAMIS 的方法，作为一种快速的流行病学筛选工具。我们使用 MRSA 作为模型生物来建立筛选策略。我们分析了过去 20 年在瑞典西南部地区最常见的 19 种脉冲场凝胶电泳（PFGE）类型中的 19 种具有代表性的、特征良好的 MRSA 菌株，使用 MALDI-TOF MS。共使用了 111 株 MRSA 菌株，使用 VITEK MS RUO/SARAMIS 为 19 种 PFGE 特异性 Superspectrum 创建了 19 种。在进行最终分析之前，将这 19 种 Superspectrum 组合成 10 个显示相似峰模式的组，此后称为"MALDI 类型"。我们分析了 255 株 MRSA 菌株，以测试构建的 Superspectrum/MALDI-type 数据库。如果匹配的峰数量超过阈值（对应于 Superspectrum 中的匹配峰数量）的 65%，则认为该菌株与 MALDI-type 的匹配为阳性。将菌株正确分配到 MALDI-type 的中位数峰值匹配值为 78%（范围为 65.3-100%）。总共有 172 株（67.4%）被正确分配到 MALDI-type，只有 5.5%的菌株被错误地分配到与菌株的 PFGE-type 不符的另一个 MALDI-type。我们设想这种方法可以作为一种经济有效的步骤，作为 MRSA 分离株分型方案中的第一步筛选策略，以排除分离株的流行病学相关性，或识别进一步分型的需要。
