Abstract:

In this study, a total of 90 isolates of Salmonella Enteritidis, including clinical and foodborne isolates, were
collected from different areas of Shanghai during 2008 to 2012. Polymerase chain reaction (PCR) was used to investigate the
carrying rates of 9 common virulence genes not only in SPIs (SPI-1 and SPI-3) but also in virulence plasmid. In addition, an
optimized enterobacterial repetitive intergenic consensus (ERIC)-PCR was applied to subtype these isolates. The PCR results
of 90 isolates showed that the carrying rate was 100.0% for virulence genes invH, sopE and sugR, and 98.9% for iacP, avrA,
prgK and rhuM, while the carrying rate of spvB and spvC was 85.6% and 78.9% respectively. Seventeen strains belonging
to eight different Salmonella serovars were clearly differentiated by ERIC-PCR, with the Simpson’s Diversity Index up to
0.970 6. However, the ERIC-PCR profiles of 90 Salmonella Enteritidis isolates showed no difference. In conclusion, the
carrying of these virulence genes, especially sugR, invH and sopE, is very common among these isolates, demonstrating that
they pose a potential threat to human health and that ERIC-PCR can be applied to the molecular classification of different
Salmonella serovars, but not for Salmonella Enteritidis.

Key words: Salmonella Enteritidis, virulence genes, ERIC-PCR