Miled R.B.,Agence Nationale Of Securite Sanitaire Anses Laboratoire Of Securite Des Aliments |
Guillier L.,Agence Nationale Of Securite Sanitaire Anses Laboratoire Of Securite Des Aliments |
Neves S.,Agence Nationale Of Securite Sanitaire Anses Laboratoire Of Securite Des Aliments |
Augustin J.-C.,National Veterinary School of Alfort |
And 2 more authors.
Food Microbiology | Year: 2011
Cells of six strains of Cronobacter were subjected to dry stress and stored for 2.5 months at ambient temperature. The individual cell lag time distributions of recovered cells were characterized at 25 °C and 37 °C in non-selective broth. The individual cell lag times were deduced from the times taken by cultures from individual cells to reach an optical density threshold. In parallel, growth curves for each strain at high contamination levels were determined in the same growth conditions. In general, the extreme value type II distribution with a shape parameter fixed to 5 (EVIIb) was the most effective at describing the 12 observed distributions of individual cell lag times. Recently, a model for characterizing individual cell lag time distribution from population growth parameters was developed for other food-borne pathogenic bacteria such as Listeria monocytogenes. We confirmed this model's applicability to Cronobacter by comparing the mean and the standard deviation of individual cell lag times to populational lag times observed with high initial concentration experiments. We also validated the model in realistic conditions by studying growth in powdered infant formula decimally diluted in Buffered Peptone Water, which represents the first enrichment step of the standard detection method for Cronobacter. Individual lag times and the pooling of samples significantly affect detection performances. © 2010 Elsevier Ltd.