1999年3月, 青森県内の工場で製造されたイカ菓子による集団食中毒事件が発生した.原因菌は, Salumonella OranienburgとS. Chesterであり, 患者は全国46都道府県の1,634名にのぼった.この事件に関連し, 原因食品と製造工場, ならびに原料イカ輸入港周辺と工場周辺などの環境について検査を行った.分離菌について, 生化学的性状, 薬剤感受性試験, PCR法による病原遺伝子検索, PFGEによる遺伝子解析, 耐熱性, 耐乾燥性, 食塩耐性試験などを実施し疫学的考察を試みる一方, 本事例と県内の散発サルモネラ症との関連を考察した.その結果, 工場の高い汚染が判明するとともに, 輸入港付近の海面のゴミと海鳥の糞そして原因工場の下水から, 患者, 食品由来と同一と考えられるS.Oranienburgが分離され, 本事件との関連性が示唆された.環境からはS.Chesterは分離されなかった.また, 分離菌は40℃ 以下の保存ではその菌数に大きな減少はなく, 乾燥には強く, 海水中では長期間生存が可能と考えられた.さらに, 散発サルモネラ症の監視がdiffuse outbreakの発見に有用である可能性が示唆された.

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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.

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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.

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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.

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