Survival of Salmonella Typhi and Shigella dysenteriae in dehydrated infant formula.

James B Day, Devang Sharma, Nusrat Siddique, Yun-Yun D Hao, Errol A Strain, Robert J Blodgett, Sufian F Al-Khaldi

Division of Microbiology, Office of Regulatory Science, Center for Food Safety and Applied Nutrition, Food and Drug Administration, College Park, MD 20740-3835, USA.

Journal of food science 2011 Aug

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Powdered infant formula has previously been linked to the transmission of various bacterial pathogens in infants resulting in life-threatening disease and death. Survival studies of 2 common foodborne pathogens, Salmonella enterica serovar Typhi and Shigella dysenteriae, in powdered infant formula have not been previously studied despite the potentially devastating consequences from ingestion of these organisms, particularly by newborns, in case of a natural or deliberate contamination event. Therefore, to better predict the risk of S. Typhi and S. dysenteriae infection from consumption of infant formula, the present study was undertaken to determine survival of these microorganisms in dry infant formula under varying atmospheric conditions. A 2-strain cocktail of S. Typhi and a 3-strain cocktail of S. dysenteriae were stored for up to 12 wk in dehydrated infant formula in an ambient air or nitrogen atmosphere. Viable counts of S. Typhi at 12 wk in infant formula revealed a 2.9- and 1.69-log decrease in ambient air and nitrogen atmosphere, respectively. Viable counts of S. dysenteriae at 12 wk in infant formula revealed a 0.81- and 0.42-log decrease in ambient air and nitrogen atmosphere, respectively. These results show that S. Typhi and S. dysenteriae can remain viable for prolonged periods of time in powdered infant formula, and the presence of nitrogen enhances survival. Our goal in this work was to study the survival of S. Typhi and S. dysenteriae in dehydrated storage conditions in infant formula. This interest is partially generated by the possibility of using these 2 microorganisms to deliberately contaminate the food supply. The outcome of this study will help us to have a better idea how to respond and react to the risk of deliberate food contamination. Journal of Food Science © 2011 Institute of Food Technologists® No claim to original US government works.

Citation

James B Day, Devang Sharma, Nusrat Siddique, Yun-Yun D Hao, Errol A Strain, Robert J Blodgett, Sufian F Al-Khaldi. Survival of Salmonella Typhi and Shigella dysenteriae in dehydrated infant formula. Journal of food science. 2011 Aug;76(6):M324-8