The purpose of this study was to evaluate the QUALIBAX^TM Q7 System (BAX system) for detecting non-O157 Shiga toxin-producing Escherichia coli (STEC) serogroups (O26, O103, O111, O121, O145) and STEC O157. The BAX system real-time PCR assay STEC suite was evaluated, including a screening assay for the stx and two panel assays to identify the target serogroups. For STEC O157, BAX system real-time PCR assay E. coli O157 : H7 was used. The BAX system assay was found to detect STEC O26, O103, O111, O121, O145 and O157 in pure culture. Each assay was 100% inclusive for the STEC strains used. And no cross-reactivity was observed. Sensitivity of a screening assay for the stx was ≧1.8×10³ CFU/ml in cultures of ground beef or lettuce. E. coli O157 : H7 was detected at a level of ≧1.8×10⁴ CFU/ml. On a collaborative study, the performance of the BAX system assay was compared with that of a culture method for detection of STEC O26, O111 and O157 in ground beef and lettuce. Sensitivity of the BAX system method was better than a culture method. These results suggest that the BAX system can be used as a rapid method for detecting STEC in food samples.

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調製された乳幼児用食品にCronobacter sakazakii を接種し，25℃，10℃，5℃の温度に48時間保存し，これらの保存期間中におけるC. sakazakiiの挙動を検討した．その結果，調製された乳幼児用食品の野菜粥(VRP)，混合野菜と小麦ペースト(MVWP)，レバ-・野菜と小麦ペースト(LVWP)中でのC. sakazakiiの挙動は，25℃ではいずれも急激な増殖が認められたのに対し，5℃と10℃では保存期間中菌数の増殖は認められなかった．一方，リンゴ果汁(AJ)では他の乳幼児用食品3種の結果と異なり，いずれの保存温度でも菌数の減少が観察され，特に25℃では著しい減少が認められた．以上のことより，乳幼児用食品4種のうち，AJを除き，VRP, MVWP, LVWPでは，室温(25℃)において急激な増殖が確認されたことから，これらの乳幼児用食品を調製した後には室温に長時間放置せず，速やかに消費することが感染リスクの低減になるものと考えられた．

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