Characterization of Salmonella enteritidis with pulsed-field gel electrophoresis in China

Objective To understand the pulsed-field gel electrophoresis (PFGE) patterns of the clinical isolates of Salmonella enteritidis and their epidemiological characteristics in China and provide evidence for the laboratory based detection of food borne diseases outbreak and response effort. Methods Molecular typing of 981 Salmonelle enteritidis strains isolated in 13 provinces from 2004 to 2012 were conducted according to PFGE protocol published on PulseNet and epidemiological analysis was conducted. Results The chromosomal DNA of 981 Salmonella enteritidis strains were digested with XbaⅠrestriction endonuclease and 126 PFGE patterns were observed. The discriminatory index (D) was 0.8336 for PFGE typing method. The predominate patterns of PFGE included JEGX01.CN0003, JEGX01.CN0001, JEGX01.CN0002, JEGX01.CN0005 and JEGX01.CN0016. Of 126 patterns, JEGX01.CN0003、JEGX01.CN0001and JEGX01.CN0150 were related with outbreaks caused by Salmonella enteritidis. Common bands (0.8%) of 655 kbp, 325 kbp, 310 kbp, 245 kbp, 178 kbp and 110 kbp were found in the predominant patterns. Conclusion There were predominant PFGE patterns among the Salmonella enteritidis strains isolated in China, however, double or multiple endonucleotidases analysis of PFGE is necessary for outbreak detection due to the limited discriminatory power of single XbaⅠdigestion.