目的：了解我国北京、上海、沈阳三市福氏志贺菌4c的生化特征、毒力基因携带情况及其遗传多态性。方法选择来自上述三市的76株福氏志贺菌4c，采用玻片凝集法，使用日本生研血清和瑞典MASF单克隆血清确定血清型，API 20E试纸条进行生化鉴定，应用PCR技术检测该血清型携带福氏志贺菌12个毒力基因情况，利用多位点序列分型（MLST）技术了解其基因型别特征。结果所测菌株日本生研血清凝集抗原结构式为（Ⅳ：7，8）；MASF单克隆抗血清结果为B＋，Ⅳ-Ⅰ＋，7（8）＋。福氏志贺菌4c在吲哚、蜜二糖和阿拉伯糖发酵实验呈现不同的生物学特性，吲哚实验阳性率为17．11％；蜜二糖发酵实验弱阳性率为3．9％；阿拉伯糖发酵实验弱阳性率为22．37％。12个毒力基因携带率为89．47％～100％，MLST分型均为ST245型。结论福氏志贺菌4c是一种抗原结构式为（Ⅳ：7，8）的志贺菌新亚型；生化反应以发酵葡萄糖和分解甘露醇为主；携带有多种志贺菌相关的毒力基因；ST分型一致，提示该菌型可能由ST270克隆型进化而来。%Objective To study the serotype , biochemical characteristics , virulence gene and multilocus sequence typ-ing(MLST) of S.flexneri 4c in Beijing, Shanghai and Shenyang .Methods Seventy-six strains of S.flexneri 4c isolated from stool samples which had been collected from above-mentioned cities of China were identified with Denka Seiken serum and MASF monoclonal serum .Biochemical characteristics of each strain were identified by API 20E test strip and PCR technology was used for detecting 12 pair virulence genes of S.flexneri.MLST was used to analyze the characteristics . Results The serum agglutination antigen structure of S.flexneri 4c was(Ⅳ:7,8).MASF:B+,Ⅳ:Ⅰ+,7 (8) +.S.flexneri 4c developed different results in biochemical reactions and carried different rates of virulence genes , respectively .The IND test positive rate was 17.11%; MEL weakly positive rate was 3.9%, and ARA test weakly positive rate was 22.37%. Virulence genes were carried at a rate of 89.47% -100%, MLST typing was ST245.Conclusion S.flexneri 4c with serum agglutination antigen structure (Ⅳ:7,8) is a new serotype of S.flexneri.The main biochemical reactions are glucose fermentation and mannitol decomposition .A variety of Shigella related virulence genes are carried .MLST generation is consistent,suggesting that the bacteria might have evolved from ST 270 cloning.
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