Outbreak investigations demand a fast and discriminative typing method. MALDI-TOF MS has been shown to be a rapid, easy and inexpensive method of subtyping MRSA.The aim of the present study is to explore whether it is possible to subdivide isolates of MRSA CC398, commonly livestock associated, using an enhanced version of the MALDI-TOF MS typing method that we previously described (Østergaard et al, 2015). We included MALDI-TOF spectra from 378 isolates of MRSA belonging to CC398, of which 322 were epidemiologically independent. We identified 17 peaks as discriminatorily useful and could therefore reliably subdivide the isolates into 23 subtypes, including a distinct type corresponding to a strain from an unusual and initially undiscovered hospital outbreak. Whole genome sequencing was carried out for 193 of the isolates and compared with both the spa type and an antibiogram of these strains. The proposed MALDI-TOF subdivision method for MRSA CC398 was found to be more discriminative than both spa typing and resistotyping, and had a high negative predictive value for ruling out a close genetic relationship between pairs of strains with different MALDI-TOF types. We conclude that the MALDI-TOF-based typing method can be used for rapid and inexpensive routine subdivision of MRSA belonging to CC398.

中文翻译：

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使用MALDI-TOF MS对MRSA CC398分离株进行细分。

爆发调查需要一种快速而有区别的打字方法。MALDI-TOF MS已被证明是一种快速，简便且廉价的MRSA分型方法。本研究的目的是探讨使用MRSA的增强版对MRSA CC398分离株（通常与家畜相关）进行细分的可能性。我们之前描述的MALDI-TOF MS分型方法（Østergaard等，2015）。我们纳入了来自CC398的378个MRSA分离株的MALDI-TOF谱图，其中322个在流行病学上是独立的。我们鉴定出17个峰具有区分性，因此可以将这些分离株可靠地细分为23个亚型，包括与来自罕见且最初未发现的医院暴发的菌株相对应的独特类型。对193个分离株进行了全基因组测序，并与水疗类型和这些菌株的抗菌谱进行了比较。发现针对MRSA CC398的拟议MALDI-TOF细分方法比水疗分型和电阻分型更具判别力，并且对于排除不同MALDI-TOF类型的菌株对之间的密切遗传关系具有很高的阴性预测价值。我们得出的结论是，基于MALDI-TOF的分型方法可用于对属于CC398的MRSA进行快速且廉价的常规细分。并且对于排除不同MALDI-TOF类型的菌株对之间的密切遗传关系具有很高的负面预测价值。我们得出的结论是，基于MALDI-TOF的分型方法可用于对属于CC398的MRSA进行快速且廉价的常规细分。并且对于排除不同MALDI-TOF类型的菌株对之间的密切遗传关系具有很高的负面预测价值。我们得出的结论是，基于MALDI-TOF的分型方法可用于对属于CC398的MRSA进行快速且廉价的常规细分。