Yoshihiro Kuwabara

Occurrence of Bacillus cereus in Meat Products, Raw Meat and Meat Product Additives

One thousand nine hundred and sixty three samples of meat products, raw meat and meat product additives from different slaughterhouses, meat processing factories and retail meat shops in six prefectures of Japan, were examined for the presence and number of Bacillus cereus . Although B. cereus was found in meat products (18.3%) and raw meat (6.6%), the contamination levels were generally lower than 102 per gram. In contrast, meat product additives showed contamination levels ranging from 102 to 104/g with the highest values (104/g) in samples of spices and animal proteins. On the basis of these results, we suggest that the main source of B. cereus contamination in meat products is contaminated meat product additives.

A PCR assay based on a sequence-characterized amplified region marker for detection of emetic Bacillus cereus.

A PCR assay for the detection of Bacillus cereus strains able to produce an emetic toxin (cereulide) was developed in this study based on a sequence-characterized amplified region (SCAR) derived from a random amplified polymorphic DNA (RAPD) fragment. One of the RAPD fragments generated was selected, cloned, and sequenced. A set of PCR primers was newly designed from the SCAR obtained (the sequence of the cloned RAPD fragment) and used in this assay. To determine the specificity of the assay, 30 different B. cereus strains, 8 other Bacillus strains (of six species), and 16 other non-Bacillus strains (from 16 genera) were tested. Results were positive for every emetic B. cereus strain and for only one nonemetic B. cereus strain. For all other bacterial strains, results were negative. Bacterial DNA for PCR was prepared by a simple procedure using Chelex 100 resin from the bacterial colony on the agar plate or from culture after growth in brain heart infusion medium. This PCR assay enabled us to detect the bacteria of emetic B. cereus grown on agar plates but not the bacteria of nonemetic B. cereus. To test this PCR assay for the monitoring of the emetic bacteria, 10 to 70 CFU of B. cereus DSM 4312 (emetic) per g of food was inoculated into several foods as an indicator, followed by a 7-h enrichment culture step. Because this PCR assay based on the SCAR derived from the RAPD fragment was able to detect bacterial cells, this assay should be useful for rapid and specific detection of emetic B. cereus.

Cytokine profile in a premature infant with systemic Bacillus cereus infection

Bacillus cereus is a large aerobic, Gram-positive, spore-forming rod that can be isolated from any substance in the environment, and has been identified as a cause of food-borne disease. B. cereus does not usually develop severe and systemic infection in immunocompetent hosts. In contrast, systemic infection can arise in immunocompromised hosts. Systemic infection of B. cereus has a high mortality rate, especially in premature infants. We encountered an extremely preterm infant with fulminant systemic B. cereus infection. As in previous reports, the present patient developed systemic B. cereus infection and died within 1 week of life. We investigated the serum cytokine profile in order to identify a defective immune response in the patient, but we found a strong response involving cytokine production in the patient. We report herein the bacteriological and immunological findings in the premature infant who developed systemic fulminant infection of B. cereus.

Exposure of Workers to TPN during Application Using Different Spraying Methods.

アスパラガスに対してTPN (クロロタロニール: chlorothaloni1) 製剤を動力噴霧機による歩行散布とスピードスプレーヤにより散布した時の散布作業者の被曝状況を比較・検討した。その結果, 動力噴務機による散布者の身体各部位への農薬付着量は, 同一量の薬液をスピードスプレーヤにより散布した場合よりも推定全身被曝量は10倍以上多く, 散布作業時間も数倍必要とした。さらに, 散布後の圃場内のTPNの消長について測定し, 再入園時の農薬被曝の可能性について考察を行うために, スピードスプレーヤによる散布圃場内のTPN残留量を測定した。アスパラガス葉の農薬は, 散布1時間後から1日後にかけて1/3に急減したが, その後の減少は非常に緩やかであった。また, 圃場内の気中農薬はTPN濃度は, 散布4時間後には散布1時間後の1/3以下になり, 測定箇所によってはTPNは検出されなかった。このことから散布後1日以降の再入園にさいしては, 特に茎葉との接触を避けるように作業すべきものと考えられた。

Exposure of Spraying and Reentering Workers in Apple Orchard to Dichlorvos.

30aのリンゴ園にスピードスプレイヤーによりDDVP乳剤を有効成分として500g散布した時の散布作業者の農薬曝露状況を知るとともに, 散布後の圃場内への立入り者の農薬曝露状況を検討した。散布作業者の農薬被曝は頭部と上肢に多く認められ, 推定全身被曝量は散布量の0.0009%に相当する4.4mg (56μg/kg) であり, 適切な防除衣を着用して作業すればほとんど健康影響はないものと思われた。さらに, 散布終了1時間, 6時間, 1日, 2日および4日後に2名がこの圃場内に30分間立入り巡回した。その結果, 散布1時間後の再入園にさいしては全身的に若干の農薬曝露が認められ, それらの推定全身暴露量は105～120μg (1.8～2.3μg/kg) であった。しかし, 6時間以降の立入りにさいしては身体への曝露は認められなかった。再入園時の気中DDVP濃度は1時間後には平均13.9μg/m3であったが, 6時間後には9分の1程度に減少し, 1日後には検出されなかった。また, 葉面DDVP残留量は1時間後で331ng/cm2であったが, その減衰は速く, 6時間後には7分の1に減少し, 2日後には検出されなかった。これらのことから1時間後の再入園にさいしては, 若干の呼吸器曝露も示唆されるが, 主に葉との接触による曝露が重視される。DDVPは揮発しやすく, 分解されやすいことから, 6時間以降には接触によるDDVPの作業者への曝露は認められず, また呼吸器曝露もほとんどなくなるものと考えられた。以上のことから, DDVPに関しては散布1日後の圃場へ再入園してもほとんど安全上の問題はないものと考えられた。