Purpose: To evaluate the performance of the 3M™ Molecular Detection Assay (MDA) and a variety of pre-enrichment media for effective recovery of Salmonella from serrano peppers.
Methods: Salmonella serotypes Salmonella Typhimurium, Salmonella Agona, Salmonella Poona and Salmonella Newport isolated from farm environments were used to artificially inoculate serrano peppers (0.89 - 1.06 CFU/g). Twelve inoculated media-only, non-inoculated peppers or inoculated peppers samples were analyzed by both the MDA and the FDA-BAM method, using in each case 5 different pre-enrichment media (D/E Broth, UPB, Lactose Broth, BPW and BPW-ISO). Sample size for peppers was standardized to 60 g (4 peppers), and combined with 200 ml of broth (FDA BAM protocol). Results for detection methods were compared using McNemar’s test for paired data, while media results were compared using the Chi-square test for unpaired data (α=0.05).
Results: A total of 180 samples were analyzed. For inoculated samples, following the MDA and FDA-BAM protocols yielded 114 and 120 positive results, respectively, reflecting no significant difference (P > 0.05) between detection methods. When using the recommended media for pre-enrichment (BPW-ISO), no false positive or false negative results were found by MDA, while 10 false negative and 3 false positive results were obtained when the other broths were used. No significant difference (P > 0.05) was observed among pre-enrichment media results.
Significance: For detection of Salmonella in serrano peppers, the MDA method provides fast and accurate results that are equivalent to those obtained by the FDA-BAM reference method. Using BPW-ISO as pre-enrichment media ensures its best performance.