Rapid Detection of Listeria monocytogenes in Food by PCR

A polymerase chain reaction (PCR) assay targeting the hly gene was developed to detect Listeria monocytogenes. The PCR product was detected in 35 L monocytogenes strains and not in other Listeria spp, including innocua, ivanovii and welshimer and also not in non-Listeria species, indicating that this method was highly specific for L. monocytogenes. The detection limit of the PCR assay was 7.3 CFU/μl of pure cell culture. The PCR assay could detect 4 CFU of L. monocytogenes in the contaminated pork and vegetable (1g) and milk (1ml). From 285 samples, 17 samples were proved positive for L. monocytogenes by the PCR method, and the results were quite consisted with those detected by conventional biochemical testing. The PCR assay is highly sensitive, specific, rapid and accurate and can be used for rapid detection of L. monocytogenes in food.