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.
A total of 88 domestic and import chickens were subjected for vancomycin-resistant enterococci (VRE). VanA type VRE were detected from one Brazilian chicken and two Thai chickens. VanC type VRE were detected from one Chinese chicken, four Brazilian chickens and eleven Japanese chickens. The MIC value of VanA type VRE strains were hyper resistance to vancomycin (>256μg/ml) and susceptible to teicoplanin (<6μg/ml). VanA type VRE strains isolated from chickens were analyzed by PCR-restriction fragment length polymorphism (PCR-RFLP), using four kinds of restriction endonucleases. The result suggested that these strains showed the same DNA banding pattern. According to the result of randomly amplified polymorphic DNA (RAPD), two strains of VanA type VRE detected from Thai chickens one seemed to be the same DNA banding pattern and the other different DNA anding pattern from Brazilian strain. According to the result of pulsed-field gel electrophoresis (PFGE), three strains of VanA type VRE were a kind of different DNA banding pattern. VanC type VRE strains indicated individual pattern using RAPD and PFGE, and were not able to be distinguished between Japanese and import strains. Our investigation shows that VRE were detected from domestic and import chickens, and had already been confirmed to be distributing the contaminated chickens throughout the country.
Fifty-one Campylobacter jejuni strains (thirty-five were derived from three poultry processing plants in 1998, and sixteen were from three food poisoning cases that occurred in Shiga prefecture in 1998) were examined by pulsed-field gel electrophoresis (PFGE) analysis. The SacII digest profile was compared with the result of serotyping. As PFGE was distinguishable to all strains including the untypable ones by serotyping, PFGE was more discriminatory than serotyping. Our conclusion is that PFGE will be useful for epidemiological investigation ofCampylobacter jejunistrains identified untypable by serotyping.
Microbial investigation was carried out on 60 samples of frozen chilled foods retailed in Osaka City from August to November in 1998. The data was evaluated by comparing with the data of a standard inspection of frozen foods retailed in the city from 1994 to 1997. As a result, heated products before freezing except for cabbage rolls were not bacterially contaminated like frozen foods. In contrast, cabbage rolls were heavily contaminated because these were repacked or unpacked at stores before selling. On the other hand, unheated products were more contaminated than frozen foods. The result showed two important points to keep frozen chlled foods sanitary. First, heated products before freezing should be packed sanitarily and be well kept before selling. Second, unheated products before freezing should be made of sanitary materials; furthermore, they should be labeled as frozen foods and treated in accordance with the standard of the food sanitation law.