title: Modeling the behavior of Listeria monocytogenes during enrichment in half Fraser broth; impact of pooling and the duration of enrichment on the detection of L. monocytogenes in food.
abstract: A stochastic model describing the growth of Listeria monocytogenes during enrichment in half Fraser was developed for the purpose of estimating the effects of modifications to the first enrichment step of the EN ISO 11290-1 detection method. Information pertaining to the variability of growth rates, physiological state of the cell, and the behavior of individual cells contaminating the food were obtained from previously published studies. We used this model to investigate the impact of pooling enrichment broths (wet pooling) on the performance of the standard method. For validation of the model, the numbers of L. monocytogenes occurring in 88 naturally contaminated foods following pre-enrichment were compared to model-simulated microbial counts. The model was then used to perform simulations representative of the natural contamination observed for smoked salmon in the European baseline survey of 2010-2011. The model-estimated L. monocytogenes levels following individual enrichment or following the pooling of five broths where only one would be contaminated were compared. The model indicated a 10% loss of method sensitivity resulting from wet pooling. The model also predicted a 5% decrease in the sensitivity of the method when the duration of the enrichment was reduced from 24 to 22 h.
authors.affiliation: Université Paris-Est, Ecole Nationale Vétérinaire d'Alfort, Maisons-Alfort, F-94704, France; Université Paris-Est, Anses, Laboratory for Food Safety, Maisons-Alfort, F-94700, France. Electronic address: jean-christophe.augustin@vet-alfort.fr.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Augustin
authors.affiliation: Atlantic Food and Horticulture Research Centre, Agriculture and Agri-Food Canada, Kentville, Nova Scotia, B4N 1J5, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Kalmokoff
authors.affiliation: Atlantic Food and Horticulture Research Centre, Agriculture and Agri-Food Canada, Kentville, Nova Scotia, B4N 1J5, Canada.
authors.forename: Timothy
authors.initials: T
authors.lastname: Ells
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, Maisons-Alfort, F-94700, France.
authors.forename: Sandra
authors.initials: S
authors.lastname: Favret
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, Maisons-Alfort, F-94700, France.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Desreumaux
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, Maisons-Alfort, F-94700, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Decourseulles Brasseur
authors.affiliation: Université Paris-Est, Anses, Laboratory for Food Safety, Maisons-Alfort, F-94700, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Gnanou Besse
mesh_terms: D015169:Colony Count, Microbial; D003470:Culture Media / Q000737:chemistry*; D005516:Food Microbiology / Q000379:methods*; D007700:Kinetics; D008089:Listeria monocytogenes / Q000254:growth & development* / Q000302:isolation & purification* / Q000378:metabolism; D015233:Models, Statistical; D017747:Seafood / Q000382:microbiology; D012680:Sensitivity and Specificity; D013269:Stochastic Processes
chemical_list: D003470:Culture Media
keywords: Analytical sensitivity; Detection method; Listeria monocytogenes; Wet pooling