title: A fast, reliable, and sensitive method for detection and quantification of Listeria monocytogenes and Escherichia coli O157:H7 in ready-to-eat fresh-cut products by MPN-qPCR.
abstract: In the present work we developed a MPN quantitative real-time PCR (MPN-qPCR) method for a fast and reliable detection and quantification of Listeria monocytogenes and Escherichia coli O157:H7 in minimally processed vegetables. In order to validate the proposed technique, the results were compared with conventional MPN followed by phenotypic and biochemical assays methods. When L. monocytogenes and E. coli O157:H7 were artificially inoculated in fresh-cut vegetables, a concentration as low as 1 CFU g(-1) could be detected in 48 hours for both pathogens. qPCR alone allowed a limit of detection of 10(1) CFU g(-1) after 2 hours of enrichment for L. monocytogenes and E. coli O157:H7. Since minimally processed ready-to-eat vegetables are characterized by very short shelf life, our method can potentially address the consistent reduction of time for microbial analysis, allowing a better management of quality control. Moreover, the occurrences of both pathogenic bacteria in mixed salad samples and fresh-cut melons were monitored in two production plants from the receipt of the raw materials to the early stages of shelf life. No sample was found to be contaminated by L. monocytogenes. One sample of raw mixed salad was found positive to an H7 enterohemorrhagic serotype.
authors.affiliation: Department of Agriculture, Food and Environmental Sciences, University of Foggia, Via Napoli 25, 71122 Foggia, Italy.
authors.forename: Pasquale
authors.initials: P
authors.lastname: Russo
authors.affiliation: Department of Agriculture, Food and Environmental Sciences, University of Foggia, Via Napoli 25, 71122 Foggia, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Botticella
authors.affiliation: Department of Agriculture, Food and Environmental Sciences, University of Foggia, Via Napoli 25, 71122 Foggia, Italy.
authors.forename: Vittorio
authors.initials: V
authors.lastname: Capozzi
authors.affiliation: Department of Agriculture, Food and Environmental Sciences, University of Foggia, Via Napoli 25, 71122 Foggia, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Massa
authors.affiliation: Department of Agriculture, Food and Environmental Sciences, University of Foggia, Via Napoli 25, 71122 Foggia, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Spano
authors.affiliation: Department of Agriculture, Food and Environmental Sciences, University of Foggia, Via Napoli 25, 71122 Foggia, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Beneduce
mesh_terms: D019453:Escherichia coli O157 / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D057140:Fast Foods / Q000382:microbiology*; D005504:Food Analysis; D006801:Humans; D008089:Listeria monocytogenes / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity; D060888:Real-Time Polymerase Chain Reaction; D014675:Vegetables / Q000382:microbiology