Limits...
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

Frequency distribution of individual Cronobacter sakazakii lag phases fitted by gamma distribution at different growth temperatures after 50°C heat shock by 0, 5, and 10 min.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4836016&req=5

Figure 1: Frequency distribution of individual Cronobacter sakazakii lag phases fitted by gamma distribution at different growth temperatures after 50°C heat shock by 0, 5, and 10 min.

Mentions: Figure 1 shows the fitted Gamma distributions for lag phase of single cells of Cronobacter sakazakii as a function of temperature and heat treatments. For the same growth temperature, the variability of the lag phase increased as the severity of heat shock increased. For example, at 5°C, the lag phase of the untreated samples ranged from 45 to 125 h whereas it ranged from 80 to 420 h for cells heat shocked at 50°C for 5 min and from 176 to 650 h for cells heat shocked at 50°C for 10 min. As the growth temperature increased, the distributions for lag phase became less variable (Figure 1). Similar results were obtained for the higher inoculum size (i.e., 50 cells) although the distributions were narrower; reflecting the smaller standard deviations than those of 1 cells (data not shown).


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)

Frequency distribution of individual Cronobacter sakazakii lag phases fitted by gamma distribution at different growth temperatures after 50°C heat shock by 0, 5, and 10 min.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 1: Frequency distribution of individual Cronobacter sakazakii lag phases fitted by gamma distribution at different growth temperatures after 50°C heat shock by 0, 5, and 10 min.
Mentions: Figure 1 shows the fitted Gamma distributions for lag phase of single cells of Cronobacter sakazakii as a function of temperature and heat treatments. For the same growth temperature, the variability of the lag phase increased as the severity of heat shock increased. For example, at 5°C, the lag phase of the untreated samples ranged from 45 to 125 h whereas it ranged from 80 to 420 h for cells heat shocked at 50°C for 5 min and from 176 to 650 h for cells heat shocked at 50°C for 10 min. As the growth temperature increased, the distributions for lag phase became less variable (Figure 1). Similar results were obtained for the higher inoculum size (i.e., 50 cells) although the distributions were narrower; reflecting the smaller standard deviations than those of 1 cells (data not shown).

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