Optimization of a Real Time PCR based method for the detection of Listeria monocytogenes in pork meat

Abstract

The aim of this study was to optimize a Real-Time PCR protocol for a rapid detection of Listeria monocytogenes in pork meat, using reduced volumes of primary selective enrichment broth and times of incubation to decrease the cost and time for analysis. Forty-five samples of pork meat were artificially contaminated with two different levels of L. monocytogenes (1–10CFU per sample and 10–100CFU per sample), homogenized in three different volumes of Half Fraser Broth (1:3; 1:5 and 1:10) and incubated at 30°C±1°C for 5h, 8h and 24h. The detection was conducted in parallel by Real-Time PCR and the ISO standard 11290-1 methods. L. monocytogenes was detected in all the samples after 24h by Real-Time PCR method, also using reduced volumes of Half Fraser Broth. This represents a clear advantage as the time to final detection and the inherent costs were significantly reduced compared to the ISO reference method. All samples artificially contaminated were correctly detected also after 8 of incubation at 30°C±1°C in Half Fraser Broth and 24h in Fraser Broth at 37°C±1°C using cultural method.