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Investigation on the Factors Affecting Cronobacter sakazakii Contamination Levels in Reconstituted Powdered Infant
Julio Parra-Flores1, Alejandra Rodriguez1, Francisca Riffo2
1Departamento de Nutrición y Salud Pública, Universidad del Bío-Bío , Chillán , Chile.
Insights
Cronobacter sakazakii rapidly grows in reconstituted powdered infant formula (PIF), particularly at 35°C. This rapid growth highlights potential risks associated with PIF contamination and infant infections.
Area of Science:
- Microbiology and Food Safety
- Bacterial Growth Kinetics
- Infant Health and Nutrition
Background:
- Cronobacter sakazakii causes severe infections in infants, primarily those under two months old.
- Powdered infant formula (PIF) is a common vehicle for C. sakazakii transmission.
- The infectious dose for C. sakazakii is estimated around 1000 CFU, with PIF safety standards set below 1 CFU/g.
Purpose of the Study:
- To determine the lag time, generation time (GT), and growth rate of C. sakazakii in reconstituted PIF.
- To evaluate factors influencing C. sakazakii contamination levels in PIF.
- To assess the risk of bacterial proliferation in infant formula.
Main Methods:
- Inoculation of C. sakazakii into reconstituted PIF at different volumes (100 and 3000 ml).
- Incubation at controlled temperatures (22°C and 35°C) over a 24-hour period.
- Utilizing ComBase software for growth modeling and kinetic analysis.
Main Results:
- At 22°C in 3000 ml PIF, C. sakazakii exhibited a growth rate of 0.45 log CFU/h, a lag phase of 3 h, and a GT of 0.67 h.
- At 35°C in 3000 ml PIF, the growth rate increased to 0.73 log CFU/h, with a shorter lag phase of 0.45 h and GT of 0.41 h.
- Growth rates were significantly faster at 35°C compared to 22°C.
Conclusions:
- Cronobacter sakazakii demonstrates rapid growth in reconstituted PIF.
- Temperature is a critical factor influencing the proliferation rate of C. sakazakii in PIF.
- Findings underscore the importance of controlling C. sakazakii contamination in PIF to prevent infant infections.
Introduction:
Certain strains of Cronobacter sakazakii can cause serious invasive infections in children, mainly those <2 months old and fed with powdered infant formula (PIF). The infectious dose of C. sakazakii is unknown but evidence suggests that it is approximately 1000 colony forming units (CFU). PIF is currently considered safe if its end-product C. sakazakii level is <1 CFU/g. In this study, we determined the lag time, generation time (GT), and growth rate of five pooled C. sakazakii isolates to evaluate the factors affecting contamination levels in reconstituted PIF.
Methods:
1.71 log CFU/ml of C. sakazakii were inoculated into 100 and 3000 ml of reconstituted PIF and incubated at 22 and 35°C. Growth was evaluated over a 24-h period. ComBase was used for modeling.
Results:
In 3000 ml, the growth rate was 0.45 ± 0.02 log CFU/h with a lag phase of 3 ± 0.05 h and GT of 0.67 h at 22°C, while the growth rate was 0.73 ± 0.01 log CFU/h with a lag phase of 0.45 ± 0.03 h and GT of 0.41 h at 35° C.
Conclusion:
Cronobacter sakazakii grows rapidly in reconstituted PIF, especially at 35° C.
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