Evaluation of a loop-mediated isothermal amplification method for the detection of Listeria monocytogenes in dairy food


Submitted: 7 July 2017
Accepted: 13 October 2017
Published: 14 December 2017
Abstract Views: 1302
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Objective of the present study was to test the performances of a loop-mediated isothermal amplification (LAMP)-based method for the detection of Listeria monocytogenes, with particular focus on the dairy products. The specificity of the method was evaluated on 42 different Listeria spp. strains from collections, food and environmental samples. 100% (32 of 32) of the L. monocytogenes strains were correctly recognised, and none of other 10 Listeria spp. strains was misidentified. The sensitivity was evaluated on four L. monocytogenes strains from different sources. The instrument was able to detect 10-400 CFU/mL. The ability to detect low initial numbers of L. monocytogenes (0.3- 0.7 Log CFU/g) was also evaluated, in duplicate, in pasteurised milk (whole and skimmed) and dairy samples (fresh ricotta, crescenza, mascarpone, mozzarella, cottage cheese, cream cheese, taleggio, gorgonzola). The analysis was performed after 18, 24 and 48 h of incubation, and was coupled with the count of L. monocytogenes in the broth. Microbial loads were insufficient to achieve a positive result after 18 and 24 h in most of the samples; after 48 h, all the products, except taleggio and one gorgonzola sample, were identified as positive; the sensitivity of the method when applied to contaminated dairy foods was about 5 Log CFU/g. The LAMP method tested can be considered a very useful tool, as it is a costeffective and easy-functioning method. The preliminary data obtained should be confirmed with a validation process taking into account different food typologies.

Erica Tirloni, Department of Health, Animal Science and Food Safety, University of Milan
Department of Health, Animal Science and Food Safety
Cristian Bernardi, Department of Health, Animal Science and Food Safety, University of Milan
Department of Health, Animal Science and Food Safety
Francesco Pomilio, Institute for Experimental Veterinary Medicine of Abruzzo and Molise G. Caporale, National Reference Laboratory for Listeria monocytogenes
Reparto di Igiene delle Tecnologie Alimentari e dell'Alimentazione Animale, Laboratorio Nazionale di Riferimento per Listeria monocytogenes
Patrizia Cattaneo, Department of Health, Animal Science and Food Safety, University of Milan
Department of Health, Animal Science and Food Safety
Simone Stella, Department of Health, Animal Science and Food Safety, University of Milan
Department of Health, Animal Science and Food Safety
1.
Tirloni E, Bernardi C, Drago S, Stampone G, Pomilio F, Cattaneo P, Stella S. Evaluation of a loop-mediated isothermal amplification method for the detection of Listeria monocytogenes in dairy food. Ital J Food Safety [Internet]. 2017 Dec. 14 [cited 2024 Jun. 13];6(4). Available from: https://www.pagepressjournals.org/ijfs/article/view/6890

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