Research Division Food Microbial Systems, Agroscope, Bern, Switzerland.
Laboratory for Food Safety, French Agency for Food, Environmental and Occupational Health & Safety (Anses), Université Paris-Est, Maisons-Alfort, France.
Appl Environ Microbiol. 2021 Feb 12;87(5):e0266220. doi: 10.1128/AEM.02662-20. Epub 2020 Dec 18.
Currently, only 5 (SEA to SEE) out of 27 known staphylococcal enterotoxins can be analyzed using commercially available kits. Six genes (, , , , , and ), encoding putative and undetectable enterotoxins, are located on the enterotoxin gene cluster (), which is part of the Staphylococcus aureus genomic island Saβ. These enterotoxins have been described as likely being involved in staphylococcal food-poisoning outbreaks. The aim of the present study was to determine if whole-genome data can be used for the prediction of staphylococcal enterotoxin production, particularly enterotoxin G (SEG) and enterotoxin I (SEI). For this purpose, whole-genome sequences of 75 Staphylococcus aureus strains from different origins (food-poisoning outbreaks, human, and animal) were investigated by applying bioinformatics methods (phylogenetic analysis using the core genome and different alignments). SEG and SEI expression was tested using a sandwich enzyme-linked immunosorbent assay method. Strains could be allocated to 14 different Saβ types, each type being associated with a single clonal complex (CC). In addition, the Saβ type and CC were associated with the origin of the strain (human or cattle derived). The amount of SEG and SEI produced also correlated with the Saβ type and the CC of a strain. The present results show promising indications that the production of SEG and SEI can be predicted based on the Saβ type or CC of a strain. Besides having infectious properties in human and animals, S. aureus can produce different enterotoxins in food. The enterotoxins can cause vomiting and diarrhea, often involving many people. Most of these outbreaks remain undiscovered, as detection methods for enterotoxins are only available for a few enterotoxins but not for the more recently discovered enterotoxins G (SEG) and I (SEI). In this study, we show promising results that production of SEG and SEI can be predicted based on the whole-genome sequencing data of a strain. In addition, these data could be used to find the source (human or cattle derived) of an outbreak strain, which is the key for a better understanding of the role SEG and SEI play in foodborne outbreaks caused by S. aureus.
目前，只有 27 种已知葡萄球菌肠毒素中的 5 种（SEA 至 SEE）可以使用市售试剂盒进行分析。六个基因（、、、、和），编码假定的和不可检测的肠毒素，位于肠毒素基因簇（）上，该基因簇是金黄色葡萄球菌基因组岛 Saβ 的一部分。这些肠毒素已被描述为可能参与葡萄球菌食物中毒暴发。本研究旨在确定全基因组数据是否可用于预测葡萄球菌肠毒素的产生，特别是肠毒素 G（SEG）和肠毒素 I（SEI）。为此，应用生物信息学方法（使用核心基因组和不同比对进行系统发育分析）对来自不同来源（食物中毒暴发、人类和动物）的 75 株金黄色葡萄球菌的全基因组序列进行了研究。使用夹心酶联免疫吸附测定法测试 SEG 和 SEI 的表达。可以将菌株分配到 14 种不同的 Saβ 型，每种类型都与单个克隆群（CC）相关联。此外，Saβ 型和 CC 与菌株的来源（人或牛来源）相关联。产生的 SEG 和 SEI 的量也与菌株的 Saβ 型和 CC 相关。本研究结果表明，基于菌株的 Saβ 型或 CC，可以有希望预测 SEG 和 SEI 的产生。金黄色葡萄球菌除了在人类和动物中具有传染性外，还可以在食物中产生不同的肠毒素。肠毒素会引起呕吐和腹泻，通常涉及很多人。由于目前仅可检测少数肠毒素，而不能检测最近发现的肠毒素 G（SEG）和 I（SEI），因此这些暴发中的大多数仍未被发现。在这项研究中，我们展示了有希望的结果，即可以基于菌株的全基因组测序数据来预测 SEG 和 SEI 的产生。此外，这些数据可用于找到暴发菌株的来源（人或牛来源），这是更好地理解 SEG 和 SEI 在由金黄色葡萄球菌引起的食源性暴发中所起作用的关键。
