|PARRA-FLORES, J - Universidad De Chile|
|FERNANDO, G. - Complutense University Of Madrid (UCM)|
|AGUIRRE, J - Universidad De Chile|
Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2016
Publication Date: 4/19/2016
Citation: Parra-Flores, J., Juneja, V.K., Fernando, G., Aguirre, J. 2016. Variability in cell response of Cronobacter sakazakii after mild-heat treatments and its impact on food safety. Frontiers in Microbiology. doi: 10.3389/fmicb.2016.00535.
Interpretive Summary: Powdered infant formula (PIF) has been implicated as a vehicle of transmission of Cronobacter sakazakii in food poisoning outbreaks. Since no growth of this pathogen can be tolerated, we characterized the behavior of the stressed and unstressed C. sakazakii in PIF in order to predict stability and to estimate the risk of illness. Our results indicated that the previous history of the cells as well as the stress conditions before inoculation effect the lag time and growth rate of the pathogen; the probability of illness increases with the increase in initial cell numbers as well as with the mild temperature abuse conditions of the PIF. These findings will assist regulatory agencies and food industry in guarding against the pathogen in PIF as well as in improving the existing microbial risk assessment for C. sakazakii in PIF.
Technical Abstract: Cronobacter spp. have been responsible for severe infections in infants associated with consumption of powdered infant formula (PIF) and follow-up formulae (FUF). 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 less than or equal to 50 cells. This variability increased as the heat shock increased and growth temperature decreased. Obviously, variability in the growth of individual Cronobacter sakazakii cell which 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 were below 0.2 in all the cases and for inoculum size of 50 cells the mean probability of illness were, in most of the cases, was above 0.7. The probability of illness was 0.68 and 0.69 by consumption of PIF with cell survivor to 50C by 5 and 10 min, respectively.