Multiplex PCR Assay for Clade Typing of Salmonella enterica Serovar Enteritidis

Salmonella enterica serovar Enteritidis is one of the most commonly reported serovars of nontyphoidal Salmonella causing human disease and is responsible for both gastroenteritis and invasive nontyphoidal Salmonella (iNTS) disease worldwide. Whole-genome sequence (WGS) comparison of Salmonella Enteritidis isolates from across the world has identified three distinct clades, global epidemic, Central/East African, and West African, all of which have been implicated in epidemics: the global epidemic clade was linked to poultry-associated gastroenteritis, while the two African clades were related to iNTS disease. However, the distribution and epidemiology of these clades across Africa are poorly understood because identification of these clades currently requires whole-genome sequencing capacity. Here, we report a sensitive, time- and cost-effective real-time PCR assay capable of differentiating between the Salmonella Enteritidis clades to facilitate surveillance and to inform public health responses. The assay described here is limited to previously confirmed S. Enteritidis isolates.