Abstract
In March 1999, a mass food poisoning accident occurred as a result of squid chips produced by a factory in Aomori Prefecture. The causative agents were Salmonella Oranienburg (SO) and S. Chester (SC); the number of patients affected totaled 1, 634 in 46 prefectures nationwide. With respect to the accident, causal food and its manufacturer were examined as well as the environment of the related factory and the port where the material (squid) was imported. The isolates were tested for biochemical characteristics, drug sensitivities, pathogenic gene searches via the PCR method, gene analysis via pulsed-field gel electrophoresis, heat tolerance, dryness tolerance, and salt tolerance for epidemiological studies. The relationship between this case and other sporadic incidents involving Salmonella poisoning was also studied. The results revealed a high level of contamination at the factory concerned and the presence of SO, which is thought to be identical with that isolated from patients and causal food, in trash on the sea surface and the feces of sea birds near the port of importation, and in drainage water from the factory concerned, suggesting an association with the present case. SC was not isolated from the environment. The isolates remained viable up to 40deg;C, tolerant to dryness, and thought to be able to survive in a seawater environment for a prolonged period.. Moreover, the results suggest that monitoring the sporadic occurrence of Salmonella poisoning might be useful for detecting diffuse outbreaks.
