Molecular typing analysis of Salmonella typhi by pulsed field gel electrophoresis in Jiangxi Province

Objective This study was to analyze the typing characteristics of Salmonella typhi strains isolated from outbreaks in Jiangxi province in past years. Methods Pulsed field gel electrophoresis (PFGE) was used in the molecular typing of Salmonella typhi strains collected from the typhoid outbreaks in 1986, 1987, 2000 and 2003. Results The 40 isolates collected from the patients and bacteria-carriers in the outbreaks in the 4 years were divided into 16 types by PFGE. There were differences in band type of Salmonella typhi in different years and different places and even those strains collected from the same outbreak at the same place in the same year were presented with different band types. Conclusion A great variation of Salmonella typhi was revealed among different years based on the good application of PFGE in the strain molecular typing analysis. This might raise the question whether the routine used vaccine can provide full protection against the epidemics caused by various strains with different PFGE types.