A LOOP-MEDIATED ISOTHERMAL AMPLIFICATION ASSAY FOR RAPID DETECTION OF LISTERIA MONOCYTOGENES

By amplifying part of the hlyA gene, which encodes the virulence factor listeriolysin O of Listeria monocytogenes, we developed a rapid, sensitive loop-mediated isothermal amplification (LAMP) assay with a high specificity for the detection of L. monocytogenes in both its pure culture and artificially contaminated chicken specimens. The LAMP assay was highly specific for four strains of L. monocytogenes but not for 16 Listeria spp. and 13 non-Listeria strains. The LAMP assay, which required a total of 90 min for the whole procedure, was significantly faster than the conventional polymerase chain reaction (PCR) assay, which usually took 160 min. We could also directly identify the presence of L. monocytogenes through the white precipitate of magnesium pyrophosphate in the reaction tubes. Moreover, the LAMP assay was 100-fold more sensitive than the conventional PCR when they were used to detect the same region of the hlyA gene. Thus, compared with the conventional PCR assay, the LAMP assay is a relatively rapid and highly sensitive method for detecting L. monocytogenes.