PCR Detection of Salmonella enterica Serotype Montevideo in and on Raw Tomatoes Using Primers Derived from hilA

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Abstract
Salmonellae have been some of the most frequently reported etiological agents in fresh-produce-associated outbreaks of human infections in recent years. PCR assays using four innovative pairs of primers derived from hilA and sirA , positive regulators of Salmonella invasive genes, were developed to identify Salmonella enterica serotype Montevideo on and in tomatoes. Based on examination of 83 Salmonella strains and 22 non- Salmonella strains, we concluded that a pair of hilA primers detects Salmonella specifically. The detection limits of the PCR assay were 10 1 and 10 0 CFU/ml after enrichment at 37°C for 6 and 9 h, respectively. When the assay was validated by detecting S. enterica serotype Montevideo in and on artificially inoculated tomatoes, 10 2 and 10 1 CFU/g were detected, respectively, after enrichment for 6 h at 37°C. Our results suggest that the hilA -based PCR assay is sensitive and specific, and can be used for rapid detection of Salmonellae in or on fresh produce.