Sensitive and Rapid Detection of Salmonella in Stool Samples by Loop-Mediated Isothermal Amplification

Objective: A loop-mediated isothermal amplification(LAMP) assay was developed and validated forthe specific detection of Salmonella in stool samples. Methods: One set of primers were designed for recognizing8 distinct sequences on Salmonella-specific gene invA. Specificity and sensitivity of the primers in the LAMP reac-tions for Salmonella detection were determined. To compare the sensitivity and specificity of the LAMP assay,PCR was performed as control. The sensitive of LAMP assay for Salmonella detection in spiked stool samples wastested too. Two methods including monitoring turbidity and adding hydroxy naphthol blue before reaction to reac-tion tube were used to determine the negative and positive results. Results: The results showed that target DNAwas amplified and visualized by the two detection methods within 50 min at isothermal temperature 63℃. The sen-sitivity of LAMP with detection limits of 6.97 pg/μL is 10 times than that of PCR. Non-Salmonella strains wereselected for specificity and the results of the amplification were negative, showed the primers designed had a goodspecificity. Conclusion: For stool samples, the same sensitivity and specificity were observed. The LAMP methodreported here demonstrates a potential and valuable means for directly detection of Salmonella in stool samples, es-pecially for its rapidity, simplicity and low cost. The LAMP assay is suitable for rapid clinical diagnosis.