Rapid Detection and Differentiating of the Predominant Salmonella Serovars in Chicken Farm by TaqMan Multiplex Real-Time PCR Assay

Abstract

<i>Salmonella</i> has been known as an important zoonotic pathogen that can cause a variety of diseases in both animals and humans. Poultry are the main reservoir for the <i>Salmonella</i> serovars <i>Salmonella</i> Pullorum (<i>S</i>. Pullorum), <i>Salmonella</i> Gallinarum (<i>S</i>. Gallinarum), <i>Salmonella</i> Enteritidis (<i>S</i>. Enteritidis), and <i>Salmonella</i> Typhimurium (<i>S</i>. Typhimurium). The conventional serotyping methods for differentiating <i>Salmonella</i> serovars are complicated, time-consuming, laborious, and expensive; therefore, rapid and accurate molecular diagnostic methods are needed for effective detection and prevention of contamination. This study developed and evaluated a TaqMan multiplex real-time PCR assay for simultaneous detection and differentiation of the <i>S</i>. Pullorum, <i>S</i>. Gallinarum, <i>S</i>. Enteritidis, and <i>S.</i> Typhimurium. In results, the optimized multiplex real-time PCR assay was highly specific and reliable for all four target genes. The analytical sensitivity corresponded to three colony-forming units (CFUs) for these four <i>Salmonella</i> serovars, respectively. The detection limit for the multiplex real-time PCR assay in artificially contaminated samples was 500 CFU/g without enrichment, while 10 CFU/g after pre-enrichment. Moreover, the multiplex real-time PCR was applied to the poultry clinical samples, which achieved comparable results to the traditional bacteriological examination. Taken together, these results indicated that the optimized TaqMan multiplex real-time PCR assay will be a promising tool for clinical diagnostics and epidemiologic study of <i>Salmonella</i> in chicken farm and poultry products.