The incidence of outbreaks of foodborne listeriosis has indicated the need for a reliable and rapid detection of the microbe in different foodstuffs. A method combining redox potential measurement and real-time polymerase chain reaction (PCR) was developed to detectListeria monocytogenesin artificially contaminated raw milk and soft cheese. Food samples of 25 g or 25 ml were homogenised in 225 ml of Listeria Enrichment Broth (LEB) with Oxford supplement, and the redox potential measurement technique was applied. ForListeriaspecies the measuring time was maximum 34 h. The absence ofL. monocytogenescould reliably be proven by the redox potential measurement method, butListeria innocuaandBacillus subtiliscould not be differentiated fromL. monocytogeneson the basis of the redox curves. The presence ofL. monocytogeneshad to be confirmed by real-time PCR. The combination of these two methods proved to detect < 10 cfu/g ofL. monocytogenesin a cost- and time-effective manner. This method can potentially be used as an alternative to the standard nutrient method for the rapid detection ofL. monocytogenesin food.
Rapid real-time PCR detection of Listeria monocytogenes in enriched food samples based on the ssrA gene, a novel diagnostic target