Department of Medical Microbiology, University Medical Center Groningen, Groningen, The Netherlands.
Syst Appl Microbiol. 2011 Feb;34(1):58-62. doi: 10.1016/j.syapm.2010.11.005. Epub 2011 Feb 2.
Gram-positive anaerobic cocci (GPAC) are part of the commensal microbiota of humans and are a phylogenetically heterogeneous group of organisms. To evaluate the suitability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for the identification of GPAC, a database was constructed, using reference strains of commonly encountered GPAC and clinical isolates of which the sequence of the 16S rRNA gene was determined. Subsequently, the database was validated by identifying 107 clinical isolates of GPAC. Results were compared with the identifications obtained by 16S sequencing or fluorescent in situ hybridization (FISH). Strains belonging to the same species grouped together, in most cases, by MALDI-TOF MS analyses. Strains with sequence similarities less than 98% to their closest relatives, formed clusters distinct from recognized species in the MALDI-TOF MS dendrogram and, therefore could not be identified. These strains probably represent new species. Only three clinical isolates (2 strains of Finegoldia magna and 1 strain of Anaerococcus vaginalis) could not be identified. For all the other GPAC strains (96/107), reliable identifications were obtained. Therefore, we concluded that MALDI-TOF MS is an excellent tool for the identification of phylogenetically heterogeneous groups of micro-organisms such as GPAC.
革兰阳性厌氧球菌（GPAC）是人类共生微生物群的一部分，是一组具有系统发育异质性的生物体。为了评估基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）在鉴定 GPAC 中的适用性，构建了一个数据库，使用常见 GPAC 的参考菌株和 16S rRNA 基因序列确定的临床分离株。随后，通过鉴定 107 株临床 GPAC 分离株对数据库进行了验证。结果与 16S 测序或荧光原位杂交（FISH）的鉴定结果进行了比较。属于同一物种的菌株通过 MALDI-TOF MS 分析大多聚集在一起。与最近亲缘体序列相似性小于 98%的菌株在 MALDI-TOF MS 系统发育树中形成与公认物种不同的聚类，因此无法鉴定。这些菌株可能代表新的物种。只有三株临床分离株（2 株粪肠球菌和 1 株阴道拟杆菌）无法鉴定。对于所有其他 GPAC 菌株（96/107），均获得了可靠的鉴定。因此，我们得出结论，MALDI-TOF MS 是鉴定具有系统发育异质性的微生物群（如 GPAC）的优秀工具。
