Investigate behavior of E. sakazakii on produce and in juice.

Enterobacter sakazakii is known to cause meningitis, sepsis and necrotizing entercolitis in infants and other individuals with undeveloped or impaired immune systems. Illnesses have largely been associated with the consumption of reconstituted infant formula that was subsequently temperature-abused.

The bacterium has also been isolated from soil, water, processing facilities and households as well as from milk powder, cheese, meat, poultry, rice, bread, lettuce and other vegetables. Outbreaks of E. sakazakii infections have not been associated with fresh produce. However, its ability to grow at low temperatures, and its occasional presence on raw, ready-to-eat foods, raises a concern about its survival and growth on fresh-cut produce and in unpasteurized juices.

Scientists at the University of Georgia studied the survival and growth of E. sakazakii inoculated onto fresh-cut apples, cantaloupe, strawberries, watermelon, cabbage, carrots, cucumbers, lettuce and tomatoes, and in juice prepared from these fruits and vegetables. Test products were inoculated with a five-strain mixture of E. sakazakii and stored at 4 C, 12 C and 25 C. Populations of E. sakazakii were monitored over a seven-day period.

The populations of E. sakazakii either did not change or gradually decreased in produce and juice stored at 4 C. But they grew at 12 C on fresh-cut apples, cantaloupe, watermelon, cucumbers and tomatoes. Increases of 3.2 log CFU per g and 3.7 log CFU per g on fresh-cut cantaloupe and watermelon, respectively, occurred within three days at 12 C. All juices except apple, strawberry, cabbage and tomato juice supported bacteria growth at 12 C. All fresh-cut produce except strawberries, and all juices except apple, strawberry and cabbage juice, supported growth of E. sakazakii at 25 C. Populations reached 6.5 log CFU per g to 9.0 log CFU per g on fresh-cut cantaloupe, watermelon and cabbage.

E. sakazakii can grow on fresh-cut produce and in juices. Scientists are conducting studies to determine the behavior of E. sakazakii on fresh produce upon exposure to conditions and practices simulating those used in commercial processing and handling operations, and in food service and home settings. They are also evaluating sanitizers to see how effective they may be in killing E. sakazakii applied to the surface of fresh produce.

Further information. Michael Doyle, Center for Food Safety, University of Georgia, Griffin Campus, Melton Building, Griffin, GA 30223; phone: [phone]; fax: [phone]; email: [e-mail].