Evaluation of loop-mediated isothermal amplification for the rapid, reliable, and robust detection of Salmonella in produce
Document Type
Article
Publication Date
4-1-2015
Abstract
Rapid, reliable, and robust detection of Salmonella in produce remains a challenge. In this study, loop-mediated isothermal amplification (LAMP) was comprehensively evaluated against real-time quantitative PCR (qPCR) for detecting diverse Salmonella serovars in various produce items (cantaloupe, pepper, and several varieties of lettuce, sprouts, and tomato). To mimic real-world contamination events, produce samples were surface-inoculated with low concentrations (1.1-2.9CFU/25g) of individual Salmonella strains representing ten serovars and tested after aging at 4°C for 48h. Four DNA extraction methods were also compared using produce enrichment broths. False-positive or false-negative results were not observed among 178 strains (151 Salmonella and 27 non-Salmonella) used to evaluate assay specificity. The detection limits for LAMP were 1.8-4CFU per reaction in pure culture and 104-106CFU per 25g (i.e., 102-104CFU per g) in produce without enrichment, comparable to those obtained by qPCR. After 6-8h of enrichment, both LAMP and qPCR consistently detected these low concentrations of Salmonella of diverse serovars in all produce items except sprouts. The PrepMan Ultra sample preparation reagent yielded the best results among the four DNA extraction methods. Upon further validation, LAMP may be a valuable tool for routine Salmonella testing in produce. The difficulty of detecting Salmonella in sprouts, whether using LAMP or qPCR, warrants further study.
Publication Source (Journal or Book title)
Food Microbiology
First Page
485
Last Page
493
Recommended Citation
Yang, Q., Wang, F., Jones, K., Meng, J., Prinyawiwatkul, W., & Ge, B. (2015). Evaluation of loop-mediated isothermal amplification for the rapid, reliable, and robust detection of Salmonella in produce. Food Microbiology, 46, 485-493. https://doi.org/10.1016/j.fm.2014.09.011