Wakabayashi Yuki, Umeda Kaoru, Yonogi Shinya, Nakamura Hiromi, Yamamoto Kaori, Kumeda Yuko, Kawatsu Kentaro
Bacteriology Section, Division of Microbiology, Osaka Institute of Public Health Morinomiya Center, Higashinari-ku, Osaka, Japan.
Microbiology Section, Division of Microbiology, Osaka Institute of Public Health Tennoji Center, Tennoji-ku, Osaka, Japan.
Int J Food Microbiol. 2018 Jan 16;265:23-29. doi: 10.1016/j.ijfoodmicro.2017.10.022. Epub 2017 Oct 22.
Staphylococcal food poisoning (SFP) is caused by staphylococcal enterotoxins (SEs) preformed in food materials. SE genes are encoded on mobile genetic elements and are widely found across Staphylococcus species including S. argenteus, although most SFP cases are caused by S. aureus. S. argenteus, recently discriminated from S. aureus as a novel species, are non-pigmented staphylococci phenotypically related to S. aureus. In 2014 and 2015, two independent food poisoning cases occurred in Osaka, Japan, in which non-pigmented staphylococci were predominantly isolated. Several enterotoxin genes (seb, seg, sei, sem, sen, seo, and selu2) were found in their genome and the production of SEB was confirmed by reverse passive agglutination tests. The non-pigmented isolates from patients, food handlers, food, and cooking utensils all produced the same pulsed-field gel electrophoresis pattern. These non-pigmented isolates were coagulase-positive and biochemically identical to S. aureus. We performed further genetic analysis using nucA sequencing and multi-locus sequence typing, and identified these isolates as S. argenteus. We also found that seb was encoded on the Staphylococcus aureus pathogenicity island, while seg, sei, sem, sen, seo, and selu2 were encoded on the enterotoxin gene cluster. From these results, we concluded that the two food poisoning outbreaks were SFP cases caused by S. argenteus harboring SE genes.
葡萄球菌食物中毒（SFP）是由食品原料中预先形成的葡萄球菌肠毒素（SEs）引起的。SE基因编码在移动遗传元件上，在包括银色葡萄球菌在内的葡萄球菌属中广泛存在，尽管大多数SFP病例是由金黄色葡萄球菌引起的。银色葡萄球菌是最近从金黄色葡萄球菌中区分出来的一个新物种，是表型上与金黄色葡萄球菌相关的无色素葡萄球菌。2014年和2015年，日本大阪发生了两起独立的食物中毒事件，主要分离出无色素葡萄球菌。在它们的基因组中发现了几个肠毒素基因（seb、seg、sei、sem、sen、seo和selu2），并通过反向被动凝集试验证实了SEB的产生。从患者、食品处理人员、食品和炊具中分离出的无色素菌株均产生相同的脉冲场凝胶电泳图谱。这些无色素菌株凝固酶阳性，生化特性与金黄色葡萄球菌相同。我们使用nucA测序和多位点序列分型进行了进一步的基因分析，确定这些分离株为银色葡萄球菌。我们还发现seb编码在金黄色葡萄球菌致病岛上，而seg、sei、sem、sen、seo和selu2编码在肠毒素基因簇上。根据这些结果，我们得出结论，这两起食物中毒事件是由携带SE基因的银色葡萄球菌引起的SFP病例。
