Kawase Jun, Hirai Shinichiro, Yokoyama Eiji, Hayashi Fumi, Kurosaki Morito, Kawakami Yuta, Fukuma Aiko, Sakai Tomotake, Kotani Mayuko, Asakura Hiroshi
Division of Bacteriology, Shimane Prefectural Institute of Public Health and Environmental Science, 582 Nishihamasada, Matsue City, Shimane, 690-0122, Japan.
Infectious Disease Surveillance Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama City, Tokyo, 208-0011, Japan.
Curr Microbiol. 2021 Jan;78(1):265-273. doi: 10.1007/s00284-020-02252-4. Epub 2020 Oct 23.
This study investigated the genetic and pathogenic variation of the subgroups of clade 2 strains of Shiga toxin (Stx)-producing Escherichia coli (STEC) O157. A total of 111 strains of STEC O157 isolated in Shimane prefecture, Japan, were classified in clade 2 (n = 39), clade 3 (n = 16), clade 4/5 (n = 3), clade 7 (n = 14), clade 8 (n = 17), and clade 12 (n = 22) by single-nucleotide polymorphism analysis and lineage-specific polymorphism assay-6. These results showed a distinct difference from our previous study in which clade 3 strains were the most prevalent strains in three other prefectures in Japan, indicating that the clade distribution of O157 strains was different in different geographic areas in Japan. Phylogenetic analysis using insertion sequence (IS) 629 distribution data showed that clade 2 strains formed two clusters, designated 2a and 2b. Stx2 production by cluster 2b strains was significantly higher than by cluster 2a strains (P < 0.01). In addition, population genetic analysis of the clade 2 strains showed significant linkage disequilibrium in the IS629 distribution of the strains in clusters 2a and 2b (P < 0.05). The Φ values calculated using the IS629 distribution data indicated that strains in clusters 2a and 2b were genetically different (P < 0.001). Cluster 2b strains are a highly pathogenic phylogenetic group and their geographic spread may be a serious public health concern.
本研究调查了产志贺毒素（Stx）的大肠杆菌（STEC）O157进化枝2菌株亚群的遗传和致病变异。通过单核苷酸多态性分析和谱系特异性多态性检测-6，对在日本岛根县分离出的总共111株STEC O157菌株进行分类，其中进化枝2（n = 39）、进化枝3（n = 16）、进化枝4/5（n = 3）、进化枝7（n = 14）、进化枝8（n = 17）和进化枝12（n = 22）。这些结果与我们之前的研究有明显差异，在之前的研究中进化枝3菌株是日本其他三个县最普遍的菌株，这表明日本不同地理区域O157菌株的进化枝分布不同。利用插入序列（IS）629分布数据进行的系统发育分析表明，进化枝2菌株形成了两个簇，分别命名为2a和2b。2b簇菌株的Stx2产量显著高于2a簇菌株（P < 0.01）。此外，对进化枝2菌株的群体遗传分析表明，2a和2b簇菌株在IS629分布中存在显著的连锁不平衡（P < 0.05）。利用IS629分布数据计算的Φ值表明，2a和2b簇菌株在遗传上存在差异（P < 0.001）。2b簇菌株是一个高致病性的系统发育群体，其地理传播可能是一个严重的公共卫生问题。
