PCR identification of Salmonella serovars for the E serogroup based on novel specific targets obtained by pan-genome analysis

Abstract

Accurate serotyping of Salmonella is essential for epidemiological investigations and surveillance of Salmonella infections. Compared to traditional methods, polymerase chain reaction (PCR) is more sensitive and identifies Salmonella to the serotype level. Few genes have been used as a target for PCR serotyping; thus, research to identify specific targets of common serotypes is needed. The Salmonella E serogroup contains multiple pathogenic serotypes that have been associated with recent cases of human salmonellosis. Thus, this study mined new molecular targets for rapid detection of the E serogroup of Salmonella serovars. Using pan-genome analysis and the online BLAST program, specific genes of Salmonella serovars Weltevreden, London, Meleagridis, and Senftenberg were obtained. Primer sets were evaluated by PCR using target strains, 41 nontarget Salmonella serotypes and 22 non-Salmonella strains. There were 11, 5, 5, and 1 genes specific to S. Weltevreden, S. London, S. Meleagridis, and S. Senftenberg, respectively, with detection limits as low as 102 or 103 CFU/mL per assay for pure culture. Moreover, the primer sets satisfactorily identified Salmonella serotypes in artificially contaminated foods. These results demonstrated that pan-genome analysis identified new specific targets, and PCR serotyping could be a primary screening method or a supplement to the classical detection method.