Submitted to: International Journal of Food Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/5/2009
Publication Date: 12/31/2009
Citation: Beuchat, L.R., Kim, H., Gurtler, J., Lin, L., Ryu, J., Richards, G. 2009. Cronobacter sakazakii in foods and factors affecting its survival, growth, and inactivation. International Journal of Food Microbiology. 136:204-213. Interpretive Summary: The bacterium Cronobacter sakazakii (formerly known as Enterobacter sakazakii) has been implicated in infant illness, mortality or irreversible brain damage. Some studies have shown that powdered infant formula sometimes is contaminated with this microorganism and leads to rare cases of neonatal illnesses. We conducted a series of studies to investigate the survival and growth characteristics of C. sakazakii in infant formula, infant cereal, fresh-cut produce, and juices made from fresh produce, as well as the use of sanitizers to inactivate the pathogen and the bacterium’s ability to to form biofilms and survive on infant feeding tubes and stainless steel surfaces. Over 12 months, C. sakazakii survived in dried infant formula at temperatures of between 45 and 86 degrees Fahrenheit, although it died more rapidly as moisture content increased. C. sakazakii grew in infant formulas and cereals reconstituted with milk or water and held at 54 – 86F. C. sakazakii also grew well on fresh-cut apples, cantaloupe, watermelon, cabbage, carrots, cucumbers, lettuce, and tomatoes at 77F and on some types of produce at 54F. Treatment of fresh fruits and vegetables with sanitizers caused reductions of 1.6 - 5.4 log CFU/apple, tomato, and lettuce. Cells of C. sakazakii attached to stainless steel and infant feeding tubes had increased resistance to disinfectants. Observations from these studies have contributed to a better understanding of the behavior of C. sakazakii in and on foods and on food-contact surfaces, thereby enabling the development of more effective strategies and interventions for its control.
Technical Abstract: Cronobacter sakazakii has been isolated from a wide range of environmental sources and from several foods of animal and plant origin. While infections caused by C. sakazakii have predominantly involved neonates and infants, its presence on or in foods other than powdered infant formula raises concern about the safety risks these foods represent to immuno-compromised consumers. We have done a series of studies to better understand the survival and growth characteristics of C. sakazakii in infant formula, infant cereal, fresh-cut produce, and juices made from fresh produce. Over a 12-month storage period, the pathogen survived better in dried formula and cereal at low water activity (0.25 - 0.30) than at high water activity (0.69 - 0.82) and at 4C compared to 30C. C. sakazakii grows in formulas and cereals reconstituted with water or milk and held at 12 - 30C. The composition of formulas or cereals does not markedly affect the rate of growth. C. sakazakii grows well on fresh-cut apple, cantaloupe, watermelon, cabbage, carrot, cucumber, lettuce, and tomato at 25C and on some types of produce at 12C. Treatment of fresh fruits and vegetables with sanitizers such as chlorine, chlorine dioxide, and a peroxyacetic acid-based solution causes reductions of 1.6 - 5.4 log CFU/apple, tomato, and lettuce. Cells of C. sakazakii in biofilms formed on stainless steel and enteral feeding tubes or dried on the surface of stainless steel have increased resistance to disinfectants. Death of cells in biofilms is affected by atmospheric relative humidity. Observations from these studies have contributed to a better understanding of the behavior of C. sakazakii in and on foods and on food-contact surfaces, thereby enabling the development of more effective strategies and interventions for its control.