title: Variability in Cell Response of Cronobacter sakazakii after Mild-Heat Treatments and Its Impact on Food Safety.
abstract: Cronobacter spp. have been responsible for severe infections in infants associated with consumption of powdered infant formula and follow-up formulae. Despite several risk assessments described in published studies, few approaches have considered the tremendous variability in cell response that small micropopulations or single cells can have in infant formula during storage, preparation or post process/preparation before the feeding of infants. Stochastic approaches can better describe microbial single cell response than deterministic models as we prove in this study. A large variability of lag phase was observed in single cell and micropopulations of ≤50 cells. This variability increased as the heat shock increased and growth temperature decreased. Obviously, variability of growth of individual Cronobacter sakazakii cell is affected by inoculum size, growth temperature and the probability of cells able to grow at the conditions imposed by the experimental conditions should be taken into account, especially when errors in bottle-preparation practices, such as improper holding temperatures, or manipulation, may lead to growth of the pathogen to a critical cell level. The mean probability of illness from initial inoculum size of 1 cell was below 0.2 in all the cases and for inoculum size of 50 cells the mean probability of illness, in most of the cases, was above 0.7.
authors.affiliation: Departamento de Nutrición y Salud Pública, Universidad del Bío-Bío Chillán, Chile.
authors.forename: Julio
authors.initials: J
authors.lastname: Parra-Flores
authors.affiliation: Residue Chemistry and Predictive Microbiology Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, Wyndmoor PA, USA.
authors.forename: Vijay
authors.initials: V
authors.lastname: Juneja
authors.affiliation: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile Santiago, Chile.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Garcia de Fernando
authors.affiliation: Laboratorio de Microbiología y Probióticos, Instituto de Nutrición y Tecnología de los Alimentos, Universidad de ChileSantiago, Chile; Departamento de Nutrición, Bromatología y Tecnología de los Alimentos, Facultad de Veterinaria, Universidad ComplutenseMadrid, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Aguirre
keywords: Cronobacter sakazakii; PIF/FUF; food safety; heat treatment; risk assessment; variability