Accurate Differentiation of Streptococcus pneumoniae from other Species within the Streptococcus mitis Group by Peak Analysis Using MALDI-TOF MS
Accurate Differentiation of Streptococcus pneumoniae from other Species within the Streptococcus mitis Group by Peak Analysis Using MALDI-TOF MS
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DOI：
10.3389/fmicb.2017.00698
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发表时间：
2017-04-25
影响因子：
5.2
通讯作者：
Bouza, Emilio
中科院分区：
文献类型：
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作者：
Marin, Mercedes;Cercenado, Emilia;Bouza, Emilio
尽管MALDI-TOF MS技术（基质辅助激光解吸电离飞行时间质谱法）在全球范围内报道的好处和不断改进的可用数据库，肺炎链球菌和链球菌之间的歧视密切相关的物种缓症链球菌组（SMG）使用这种方法一直是次优的。然而，在物种水平上准确鉴定这组微生物对于感染患者的适当管理非常重要。在本研究中，216 SMG分离物-101 S.肺炎球菌和115个对应于该组内的7个非肺炎球菌物种。所有分离株先前均已通过常规方法（optochin和胆汁溶解度试验）鉴定，并且在需要时通过序列分析（sodA和plys基因）确认非肺炎球菌分离株。还用MALDI Biotyper 3.1（Bruker Daltonics，不莱梅，德国）使用包含6，903个主光谱谱（MSP）的更新文库鉴定分离株。所有分析的S.使用最新的数据库，在种水平上用MALDI-TOF MS正确鉴定了肺炎球菌SMG分离株，并且还在组水平上鉴定了所有非肺炎球菌SMG分离株。已发现几个峰（4，964.32、6，888.90和9，516.46 m/z）为S的特异性峰。pneumoniae中，而一组不同的峰已被证明仅存在于S. mitis（6，839.07 m/z）和S. oralis（5，297.61、5822.53和6，839.07 m/z）。峰分析允许101/101 S的正确物质归属。pneumoniae分离株（100%）和102/105株S.缓症/口腔分离株（97.1%）。因此，实施MALDI-TOF MS加峰分析鉴定这组微生物可以提供精确的物种水平的信息，这将允许早期实施定向抗生素治疗。
Despite the benefits of MALDI-TOF MS technology (Matrix-Assisted Laser Desorption-Ionization Time-Of-Flight Mass Spectrometry) reported worldwide and the continuous improving of the available databases, discrimination between Streptococcus pneumoniae and closely related species within the Streptococcus mitis group (SMG) using this methodology has been suboptimal. However, the accurate identification at the species level of this group of microorganisms is important for the appropriate management of infected patients. In this study, 216 SMG isolates-101 S. pneumoniae and 115 corresponding to 7 non-pneumococcal species within this group-were analyzed. All the isolates had been previously identified by conventional methods (optochin and bile solubility tests) and non-pneumococcal isolates were confirmed by sequence analysis (sodA and plys genes) when required. The isolates were also identified with the MALDI Biotyper 3.1 (Bruker Daltonics, Bremen, Germany) using an updated library containing 6,903 Main Spectra Profiles (MSPs). All the analyzed S. pneumoniae were correctly identified with MALDI-TOF MS at species level using the most updated database and all the non-pneumococcal SMG isolates were also identified at the group level. Several peaks (4,964.32, 6,888.90, and 9,516.46 m/z) have been found to be specific of S. pneumoniae, whilst a different set of peaks have proved to be present only in S. mitis (6,839.07 m/z) and S. oralis (5,297.61, 5822.53, and 6,839.07 m/z). Peak analysis allowed correct species assignment of 101/101 S. pneumoniae isolates (100%) and 102/105 S. mitis/oralis isolates (97.1%). Thus, the implementation of MALDI-TOF MS plus peak analysis for the identification of this group of microorganisms may provide precise species-level information that will allow the early implementation of directed antibiotic therapy.