Rapid real-time loop-mediated isothermal amplification combined with coated activated carbon for detection of low numbers of Salmonella enterica from lettuce without enrichment

A real-time loop amplified (Rti-LAMP) DNA assay system was developed for the rapid detection of low numbers of Salmonella enterica ser. Enteritidis (S. enterica) on the leaves of romaine lettuce without enrichment. The assay involved seeding 50 g portions of leaves with various numbers of S. enterica CFU. The lowest level of DNA consistently detected by the Rti-LAMP assay was that from 25 CFU per 50 g (0.5 CFU/g) of lettuce equivalent to the DNA from 6 CFU per Rti-LAMP reaction. A standard curve was generated by plotting the Tp values (min) against the log of 6, 25, 60 and 250 CFU of S. enterica seeded onto 50 g of lettuce. The entire assay could be completed in 3.5 h.7