Study on rare Salmonella enterica Subsp.enterica serovar Senftenberg strains with H2S negativity from diarrhea patients

Objective:To investigate the genetic clone characteristics rare Salmonella enterica Subsp.enterica serovar Senftenberg(S.Senftenberg)strains with H2S negativity from diarrhea patients.Methods:A retrospective analysis was performed to explore the characteristics of biochemical test,encoding Salmonella pathogenecity island gene 1(SPI-1) and antibiotic resistance of S.Senftenberg from diarrhea patients in Shanghai Global Salm-Surv(GSS).Ribotyping comparisons were made between typical and atypical strains of S.Senftenberg using Riboprinter(RP) DNA finger printing technique.Using cluster analysis,we compared the molecular subtyping of these strains with same serotyping strains in China PulseNet dynamic database by PFGE.Results:Among 4 strains of S.Senftenberg isolated from LU-WAN district GSS-Surv hospital in 2006,there were 2 phenotype variant strains with H2S negative and lacking SPI-1.There were two different clone between the two variant strains and typical strains by RP Ribotyping.36 strains of S.Senftenberg including 4 strains from LU-WAN district were divided into 18 PFGE typing-patten by China PulseNet database.The PFGE subtype 4(1 strains) and 5(1 strains) belong to the LU-WAN's variant strains,the subtype 11(1 strains),23(strains) belong to the LU-WAN's typical strains.Cluster analysis showed the clone of variant strains was higher than that of the typical strains in genetic similarity.Conclusion:The molecular tracing source confirms that variant strains of S.Senftenberg lacking SPI-1 can induce sporadic outbreak as the typical strains.There were homologous between variant strains of S.Senftenberg with H2S negative isolated from diarrhea patients in 2006 LU-WAN district and two strains of S.Senftenberg lacking SPI-1 isolated from a food-borne disease outbreak in 2002 Shenzhen city.