U.S. Food and Drug Administration, Microbiological Sciences Branch, Southeast Food and Feed Laboratory, Office of Regulatory Science, Office of Regulatory Affairs, 60 8th St NE, Atlanta, GA, 30309, USA.
J AOAC Int. 2021 Sep 27;104(5):1381-1388. doi: 10.1093/jaoacint/qsab070.
Clostridium is a genus of Gram-positive, spore-forming, anaerobic bacteria comprising approximately 100 species. Some Clostridium spp. (C. botulinum, C. perfringens, C. tetani, and C. difficile) have been recognized to cause acute food poisoning, botulism, tetanus, and diarrheal illness in humans. Thus, rapid identification of Clostridium spp. is critical for source-tracking of contaminated food and to understand the transmission dynamics of these foodborne pathogens.
This study was carried out to rapidly identify Clostridium-like isolates by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) MS and rRNA sequencing methods.
Thirty-three Clostridium-like isolates were recovered from various baby food and surveillance samples. Species identification of these isolates was accomplished using the VITEK MS system. Sequence characterization of the 16S rRNA region was done on an ABI 3500xL Genetic Analyzer.
The VITEK MS system identified 28 of the 33 Clostridium-like isolates with a high confidence value (99.9%); no identification was observed for the remaining five isolates. Nucleotide sequencing of the 16S rRNA region identified all 33 Clostridium-like isolates. Furthermore, while characterizing the 16S rRNA gene, 11 distinct Clostridium spp. (Clostridium aciditolerans, Clostridium aerotolerans, Clostridium argentinense, Clostridium beijerinckii, Clostridium bifermentans, Clostridium butyricum, Clostridium cochlearium, Clostridium difficile, Clostridium perfringens, Clostridium sporogenes, and Clostridium subterminale) were recognized among the 33 Clostridium-like isolates. One of the Clostridium-like isolates was identified as Citrobacter amalonaticus by both diagnostic methods. The generated 16S rRNA sequences matched completely (100%) with sequences available in GenBank for Clostridium and Citrobacter species. Species identification attained using the VITEK MS for the Clostridium-like isolates was comparable to that from the 16S rRNA sequencing-based data.
The VITEK MS and 16S rRNA sequence analysis can be implemented in the species identification of Clostridium spp. isolates of public health importance.
MALDI-TOF MS and 16S rRNA sequencing can be used in the species identification of Clostridium species.
梭菌属是革兰氏阳性、产芽孢、厌氧细菌的一个属，包含大约 100 个种。一些梭菌（C. botulinum、C. perfringens、C. tetani 和 C. difficile）已被确认为导致人类急性食物中毒、肉毒中毒、破伤风和腹泻病的病原体。因此，快速鉴定梭菌属对于追踪污染食物的来源以及了解这些食源性病原体的传播动态至关重要。
本研究旨在通过基质辅助激光解吸电离飞行时间（MALDI-TOF）MS 和 rRNA 测序方法快速鉴定梭菌样分离株。
从各种婴儿食品和监测样本中回收了 33 株梭菌样分离株。使用 VITEK MS 系统对这些分离株进行种属鉴定。在 ABI 3500xL 遗传分析仪上对 16S rRNA 区进行序列特征分析。
VITEK MS 系统以 99.9%的高置信值鉴定了 33 株梭菌样分离株中的 28 株；其余 5 株分离株未鉴定出。16S rRNA 区的核苷酸测序鉴定了所有 33 株梭菌样分离株。此外，在对 16S rRNA 基因进行特征分析时，在 33 株梭菌样分离株中鉴定出 11 种不同的梭菌（Clostridium aciditolerans、Clostridium aerotolerans、Clostridium argentinense、Clostridium beijerinckii、Clostridium bifermentans、Clostridium butyricum、Clostridium cochlearium、Clostridium difficile、Clostridium perfringens、Clostridium sporogenes 和 Clostridium subterminale）。其中一株梭菌样分离株通过两种诊断方法均被鉴定为柠檬酸杆菌属的柠檬酸杆菌属。生成的 16S rRNA 序列与 GenBank 中梭菌和柠檬酸杆菌属的序列完全匹配（100%）。VITEK MS 用于梭菌样分离株的种属鉴定与基于 16S rRNA 测序的数据相当。
MALDI-TOF MS 和 16S rRNA 序列分析可用于鉴定具有公共卫生重要性的梭菌属分离株。
MALDI-TOF MS 和 16S rRNA 测序可用于梭菌属物种的鉴定。
