Rapid Detection of Salmonella enterica Subspecies enterica serovar Typhimurium by Loop Mediated Isothermal Amplification (LAMP) Test From Field Chicken Meat Samples

Abstract

Considering the importance of Salmonella enterica subsp. enterica serovar Typhimurium in the foodborne diseases, a Typhimurium specific loop mediated isothermal amplification (LAMP) test was standardized for its rapid detection in chicken meat. The Optimum results were obtained at 64^oC and 70 min temperature-time combination. The sensitivity of LAMP and PCR were compared with serial 10-fold dilution of the 100 ng of DNA. The LAMP test detected 2 pg DNA per reaction tube, whereas PCR detected 200 pg DNA per reaction. Therefore, the LAMP test was considered 100 times more sensitive than the PCR. The specificity of LAMP and PCR analyzed with six different isolates of non-Salmonella and 22 serovars of non-Typhimurium. None of these isolates were found positive by both LAMP and PCR. Twenty-eight pure isolates of Salmonella Typhimurium from diverse sources were also examined by Typhimurium specific LAMP and were all found positive. Two-hundred twenty-five field chicken meat samples were screened by cultural, PCR, and LAMP methods. The LAMP and PCR tests were performed by using DNA isolated from 8 h and 18 h enrichment samples, respectively. Typhimurium specific LAMP was shown to be in 100% correlated with cultural and PCR methods. However, LAMP test delivered the results within 26 h without sophisticated equipment while PCR and cultural methods took 48 h and 6 d, respectively. The LAMP test developed in this study has potential to detect and as well as differentiate S. Typhimurium from other Salmonella serovars.

Keywords:

• LAMP
• chicken meat
• Salmonella Typhimurium
• PCR
• DNA