2004 Volume 21 Issue 1 Pages 23-29
In Japan, there have been an increasing number of food poisoning cases caused by pathogenic-bacteria-contaminated foods containing vegetables. Enterohemorrhagic Escherichia coli O157:H7 (O157) and Salmonella are the main causative agents of such poisoning cases. The cases have been caused by not only contaminated food materials but also food contaminatedduring cooking and arrangement. For prevention of such food poisoning, the proliferation of O157, Salmonella Infantis (SI) and Salmonella Enteritidis (SE) were studied in the following conditions. 1. Proliferations of these bacteria in distilled water (DW), physiological saline (PS) and tryptic soy broth (TSB) for 2, 4, 6 and 8 hr at 25, 30 and 35°C. The bacteria could not proliferate in DW or PS but could survive at any temperature tested and proliferated 101-104 times in 8 hr at 30 and 35°C in soy broth. 2. Spinach, lettuce, cucumber, Japanese radish, cabbage, celery, turnips and leeks were cut and soaked, and the water used for soaking (instead of washing) was tested for proliferation. O157 did not proliferate in the water leeks had soaked in. SI could not proliferate in the water that celery, turnips and leeks had soaked in, but proliferated fully in the soak water from other vegetables. 3. Water samples from boiled spinach, qinggeng-cai and cabbage were tested for proliferation of SE and SI. Water samples from boiled qinggeng-cai and cabbage were found to be good media for proliferation of SI, but not for SE.