A novel multiplex PCR assay for the detection of Salmonella enterica serovar Enteritidis in human faeces

Aims:  To develop a multiplex PCR assay for the detection of Salmonella enterica serovar Enteritidis in human faeces. Methods and Results:  A total of 54 Salmonella strains representing 19 serovars and non-Salmonella strains representing 11 different genera were used. Five primer pairs were employed in the assay. Three of them targeted to the genes hilA, spvA and invA that encode virulence-associated factors. A fourth primer pair amplified a fragment of a unique sequence within S. enterica serovar Enteritidis genomes. An internal amplification control (a fragment of a conservative sequence within the 16S rRNA genes) was targeted by a fifth primer pair. The assay produced two or three amplicons from the invA, hilA and 16S rRNA genes for 19 Salmonella serovars. All Salmonella and non-Salmonella strains yielded a band of an internal amplification control. For S. enterica serovar Typhimurium, four products (the fourth from the spvA gene), and for S. enterica serovar Enteritidis five amplicons (the fifth from the sdf gene) were observed. S. enterica serovar Enteritidis was cultured from three of 71 rectal swabs from diarrhoeal patients. Five specific amplicons were generated with the multiplex PCR assay only from culture-positive faecal samples. Conclusion:  The multiplex PCR assay specifically detects S. enterica serovar Enteritidis. Significance and Impact of the Study:  This is a novel multiplex PCR assay, which contains an internal amplification control and enables concurrent survey for Salmonella virulence genes.