[Virulence genes and pathogenicity of Shigella flexneri Xv isolated in Beijing].

OBJECTIVE

To understand the biochemical characteristics, virulence genes and pathogenicity of Shigella flexneri Xv isolated in Beijing.

METHODS

61 strains of S. flexneri Xv isolated from diarrhea patients in Beijing were systematically determined through biochemical reactions and serological tests. Application of PCR technique in detection of virulence genes on ipaH, sen, virF, ial and pulsed-field gel electrophoresis (PFGE) was used to identify the related characteristics and on rat lung slices to determine its pathogenicity.

RESULTS

All of the S. flexneri Xv could ferment glucose, mannitol, melibiose and arabinose. Using serum agglutination, we found that the antigen structure was (IV: 7, 8). IpaH, sen, virF and ial that carried rates of virulence genes appeared to be 100%, 81.97%, 75.41% and 80.30%, respectively. Among 61 strains of S. flexneri Xv, the PFGE typing of Shigella bacteria could be divided into 25 belt types while the results from rat lung slices showed inflammatory change of Xv.

CONCLUSIONS

S. flexneri Xv was found that it carried high rate of Shigella virulence genes, exhibiting genetic polymorphism and highly invasive.