Objective   To investigate the significance of four genetype methods which were implicated in the molecular epidemiology study of a Shigellosis outbreak.

  Methods   Plasmid profile analysis, Plasmid DNA restriction endonuclease analysis, RA PD-PCR, Set1/set2-PCR.

  Results   The 43 isolates were subtyped to two genetypes with RAPD-PCR.They were subtyped to three genetypes with plasmid profile analysis and set1/set2-PCR, and subtyped to four genetypes with plasmid DNA restriction endonuclease analysis.35 of all isolates had same genetype.They were the epidemic strain in this outbreak.7 of all isolates had different genetypes.They were the sporadic strains which were isolated in the same time of the outbreak.The strain isolated from food had same genetype as epidemic strain.It proved that the route of transmission was contaminated food.The cook wasn't the infection source because the strain isolated from it had different genetype from epidemic strain.

  Conclusion   Genetype methods could explore the epidemiologic relationship of isolates in a Shigellosis outbreak more accurately and more profoudly.