Rapid and visual detection of Salmonella in meat using invasin A (invA) gene-based loop-mediated isothermal amplification assay

Salmonella, recognized as one of the most important foodborne bacteria has worldwide health and socio-economic impact. To prevent the occurrence of outbreaks and recall of food, a simple, rapid and robust detection test is needed. In the present study, a loop-mediated isothermal amplification (LAMP) assay was developed for rapid, sensitive and visual detection of Salmonella spp. and validated in meat using chevon as a model. The specificity of the developed LAMP was ascertained by using Salmonella and non-Salmonella strains. The developed LAMP assay was 10 fold more sensitive than conventional PCR with the analytical sensitivity of 5 fg and 50 fg of DNA, respectively. In chevon samples artificially contaminated with S. Typhimurium, the LOD of LAMP was log(10) 8.50 CFU/g, without enrichment, whereas, after short enrichment of meat for 6 h and 12 h, the sensitivity significantly improved with the detection limit of log(10) 2.50 CFU/g and log(10) 1.50 CFU/g, respectively. The current study demonstrates that the developed LAMP assay is a simple, sensitive and specific method to identify Salmonella which may be utilized in future for rapid detection of Salmonella in meat. The present study also highlights the importance of enrichment for sensitive detection of Salmonella from meat samples.