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Variability in Cell Response of Cronobacter sakazakii after Mild-Heat Treatments and Its Impact on Food Safety.

Parra-Flores J, Juneja V, Garcia de Fernando G, Aguirre J - Front Microbiol (2016)

Bottom Line: Stochastic approaches can better describe microbial single cell response than deterministic models as we prove in this study.This variability increased as the heat shock increased and growth temperature decreased.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.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Nutrición y Salud Pública, Universidad del Bío-Bío Chillán, Chile.

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.

No MeSH data available.


Related in: MedlinePlus

Mean probability of illness by consumption of PIF contaminated with a concentration of cells (taken from Figures 3C1–C3, stochastic approach at 50 h of incubation at 15°C of a single cell survivor to 50°C for 5 and 10 min). The control is also showed as untreated cells and the prevalence is included as a uniform distribution between 3 and 30%.
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Figure 4: Mean probability of illness by consumption of PIF contaminated with a concentration of cells (taken from Figures 3C1–C3, stochastic approach at 50 h of incubation at 15°C of a single cell survivor to 50°C for 5 and 10 min). The control is also showed as untreated cells and the prevalence is included as a uniform distribution between 3 and 30%.

Mentions: As expected the previous finding was affected by growth conditions and previous history of the cells (heat treatment intensity). The higher the previous heat treatment the lower the probability of illness, indeed the predicted mean probability of illness in this conditions was close to 0 (0.0006) as shows Figure 4, in contrast, untreated cells showed the higher mean probability of illness (0.165), while heat treated cells for 5 min had a mean probability of 0.003. These estimation are affected directly by the concentration of cells at the time of consumption, in this example, after 50 h of keeping the PIF at 15°C, the stochastic growth model of untreated cells (Figure 3C1–C3) predicted concentration ranged from 2282 to 32205 cells/ml (95% CI) while heat treated cells by 50°C for 10 min there were no growth (1 cell) to 3 cells/ml (95% CI), in the other hand, at 5 min of heat treatment the concentration observed was 1 to 873 cells/ml (95% CI).


Variability in Cell Response of Cronobacter sakazakii after Mild-Heat Treatments and Its Impact on Food Safety.

Parra-Flores J, Juneja V, Garcia de Fernando G, Aguirre J - Front Microbiol (2016)

Mean probability of illness by consumption of PIF contaminated with a concentration of cells (taken from Figures 3C1–C3, stochastic approach at 50 h of incubation at 15°C of a single cell survivor to 50°C for 5 and 10 min). The control is also showed as untreated cells and the prevalence is included as a uniform distribution between 3 and 30%.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4836016&req=5

Figure 4: Mean probability of illness by consumption of PIF contaminated with a concentration of cells (taken from Figures 3C1–C3, stochastic approach at 50 h of incubation at 15°C of a single cell survivor to 50°C for 5 and 10 min). The control is also showed as untreated cells and the prevalence is included as a uniform distribution between 3 and 30%.
Mentions: As expected the previous finding was affected by growth conditions and previous history of the cells (heat treatment intensity). The higher the previous heat treatment the lower the probability of illness, indeed the predicted mean probability of illness in this conditions was close to 0 (0.0006) as shows Figure 4, in contrast, untreated cells showed the higher mean probability of illness (0.165), while heat treated cells for 5 min had a mean probability of 0.003. These estimation are affected directly by the concentration of cells at the time of consumption, in this example, after 50 h of keeping the PIF at 15°C, the stochastic growth model of untreated cells (Figure 3C1–C3) predicted concentration ranged from 2282 to 32205 cells/ml (95% CI) while heat treated cells by 50°C for 10 min there were no growth (1 cell) to 3 cells/ml (95% CI), in the other hand, at 5 min of heat treatment the concentration observed was 1 to 873 cells/ml (95% CI).

Bottom Line: Stochastic approaches can better describe microbial single cell response than deterministic models as we prove in this study.This variability increased as the heat shock increased and growth temperature decreased.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.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Nutrición y Salud Pública, Universidad del Bío-Bío Chillán, Chile.

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.

No MeSH data available.


Related in: MedlinePlus