Development, and complete evaluation, of a novel Most-Probable-Number (MPN) qPCR method for accurate and express quantification of Listeria monocytogenes in foodstuffs
2015
Garrido-Maestu, Alejandro | Vieites-Maneiro, Ramón | Peñaranda, Elvira | Cabado, Ana G.
Listeria monocytogenes is still one of the most significant food-borne pathogens. The reason for this importance relies on its capacity to survive under adverse conditions, such as low pH and/or low temperature, and more important is its high lethality, which can reach 30 % of infected individuals. At present, there are several methods available for its detection and enumeration, and a great effort has been focused on the development and evaluation of detection protocols. However, most enumeration approaches, based on culture techniques, take several days to complete, and most alternative protocols do not reach the legal limit required for this bacterium (100 cfu/g). The current study presents the complete development and evaluation of a Most-Probable-Number method combined with a real-time PCR confirmation step, which may be accomplished in 28 h. The method was evaluated in five different food types at different inoculation ranges and was also compared against the ISO 11290-2: 1998 which is the internationally accepted reference method. No discrepancies were observed with respect to the expected results of either inoculated or natural samples, thus proving the suitability of the method for its direct application in the food industry for the reliable control of this pathogen. Our MPN-qPCR proved to be faster than other molecular and traditional methods, as well as to have high sensitivity, specificity and accuracy.
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