Biological characteristics and sequence typing analysis of S.flexneri 4c in Beijing, Shanghai and Shenyang of China / 军事医学

ABSTRACT

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(Ⅳ7,8).MASFB+,ⅣⅠ+,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 (Ⅳ7,8) 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.