Rapid Detection of Salmonella spp from Meat: Loop Mediated Isothermal Amplification (LAMP)

Loop-mediated isothermal amplification (LAMP) is a novel, high specific and sensitive method which amplifies nucleic acid under isothermal conditions. Salmonella is considered one of the threatening pathogens in food industries and these species are associated with distinct food poisoning called salmonellosis. Four primers (two outer and two inner primers) were designed to target six distinct regions on the target gene invA which is conserved in Salmonella species. The reaction was optimised for 60 mins at 65 ̊C. The sensitivity of the LAMP and PCR assay for Salmonella was 10 CFU/ml and 100 CFU/ml respectively. Artificial spiking of chicken meat shows detection of Salmonella even at dilution to extinction (<1 CFU/ml) immediately after spiking as well after 48hr enrichment. All the LAMP experiments were compared to PCR method. This study reports the development of a highly sensitive, specific and a rapid diagnostic assay for the detection of Salmonella from food. The developed method could be very useful for routine pathogens point of care (POC) diagnostics.

Loop-Mediated Isothermal Amplification for Salmonella Detection in Food and Feed: Current Applications and Future Directions

Loop-mediated isothermal amplification (LAMP) has become a powerful alternative to polymerase chain reaction (PCR) for pathogen detection in clinical specimens and food matrices. Nontyphoidal Salmonella is a zoonotic pathogen of significant food and feed safety concern worldwide. The first study employing LAMP for the rapid detection of Salmonella was reported in 2005, 5 years after the invention of the LAMP technology in Japan. This review provides an overview of international efforts in the past decade on the development and application of Salmonella LAMP assays in a wide array of food and feed matrices. Recent progress in assay design, platform development, commercial application, and method validation is reviewed. Future perspectives toward more practical and wider applications of Salmonella LAMP assays in food and feed testing are discussed.

Recombinase polymerase amplification combined with lateral flow dipstick for equipment-free detection of Salmonella in shellfish

Salmonella is a major pathogen that causes acute foodborne outbreaks worldwide. Seafood, particularly shellfish, is a proven source of Salmonella spp. infection because many people prefer to eat it raw or lightly cooked. However, traditional identification methods are too time-consuming and complex to detect contamination of bacteria in the food chain in a timely manner, and few studies have aimed to identify Salmonella in shellfish early in the supply chain. We herein developed a method for rapid detection of Salmonella in shellfish based on the method of recombinase polymerase amplification (RPA) combined with lateral flow dipstick (LFD), which targets the invasion gene A (invA). The RPA-LFD was able to function at 30-45 °C, and at the temperature of 40 °C, it only took 8 min of amplification to reach the test threshold of amplicons. The established method had both a good specificity and a sensitivity of 100 fg DNA per reaction (20 µL). Regarding practical performance, RPA-LFD performed better than real-time PCR. Another advantage of RPA-LFD is that it was capable of being performed without expensive equipments. Thus, RPA-LFD has potential for further development as a detection kit for Salmonella in shellfish and other foods under field conditions.