PCR VALIDATION FOR DETECTION OF Listeria monocytogenes IN RAW BEEF AND CHICKENS

Listeria monocytogenes is a zoonotic emergent microorganism in the food industry, being from great interest for the public health. The aim of this work was to validate the PCR technique for the detection of Listeria monocytogenes in raw meats of beef and chicken. The DNA extraction procedure was carried out with lisozyme, proteinase K and phenol-cloroform, starting from artificially contaminates samples. The specificity of primers LI1 and U1 was verified by the amplification of a 938bp band corresponding to a fragment of rDNA 16S; in the same way the ?primers? LF and LR amplified a band of 750bp corresponding to the hlyA gene; allowing the genus (938bp band) and species (750bp band) identification respectively. Other bacterial strains assayed did not amplify any of the Listeria specific bands. The detection limit for PCR was of 102 and 104 UFC/gr on beef and chicken meat respectively; the Gold Standard reported 102 UFC/ml in both cases. The comparison of the PCR versus the Gold Standard method reported upon chicken meat an observed concordancy of 98,43%, a sensitivity of 96,9%, an specificity of 100%, a positive predictive value of 100% and a negative predictive value of 97%; for beef all the previously parameters were 100%. This results showed the feasibility of the PCR for the quality control on raw beef and chicken.