Relationships of 76 Shigella sonnei isolates from Guizhou Province based on Pulsed Field Gel Electrophoresis (PFGE).

The 76 S. sonnei isolates from Guizhou province were analyzed by PFGE using XbaI. The interpretation of the PFGE patterns was performed with BioNumerics software using the Dice similarity coefficient. The tree indicating relative genetic similarity was constructed on the basis of the unweighted pair group method of averages (UPGMA) and a position tolerance of 1%. A PFGE pattern with one or more DNA bands different from the others was taken to be a unique PFGE pattern. The dendrogram constructed using the PFGE patterns was generated by the UPGMA algorithm using the Dice-predicted similarity value of two patterns. The corresponding PFGE pattern, serotype and background information were shown alongside the dendrogram on the right.