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首页> 外文期刊>Food microbiology >Efficacy of a post enrichment acid treatment for isolation of Escherichia coli O157:H7 from alfalfa sprouts
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Efficacy of a post enrichment acid treatment for isolation of Escherichia coli O157:H7 from alfalfa sprouts

机译：富集酸处理从苜蓿芽中分离大肠杆菌O157：H7的功效

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摘要

The enrichment, detection and isolation procedure in the current US FDA BAM have been shown effective for Escherichia coli O157:H7 in a wide variety of foods. Recently reported modifications to the enrichment protocol, including post-enrichment immunomagnetic separation (IMS) procedures have improved sensitivity of the method for alfalfa sprouts. However, cultural isolation on selective agar plates still presents a challenge in this food matrix. The focus of this study was to reduce levels of competing microflora and enhance isolation of E. coli O157:H7 on selective agars. We optimized the use of a short acid treatment after enrichment and with post-enrichment IMS beads. The optimized acid treatments were then evaluated in alfalfa sprouts artificially contaminated with E. coli O157:H7. After 5 h enrichment of alfalfa sprouts contaminated at 0.2 cfu/g, there was significant improvement in isolation on the selective plates following acid treatment of two types of IMS beads. Following 24 h enrichment of alfalfa sprouts contaminated at low levels, £ coli O157:H7 was only recovered from 8/25 samples when no IMS or acid treatments were used. The use of only the acid treatment improved recovery to 19/25 samples. Following IMS of the enrichment broths, acid treatment increased isolation to 23/25 for Pathatrix~(™) and 24/25 for BeadRetriever~(™) IMS. Acid treatment (pH 2) of the enrichment broth for 30 min or IMS beads for 7 min is a simple and rapid way to greatly improve isolation of E. coli 0157 from alfalfa sprout enrichments by reducing the interfering microflora on the selective media.
机译：目前美国FDA BAM中的富集，检测和分离程序已显示对多种食品中的大肠杆菌O157：H7有效。最近报道的对富集方案的修改，包括富集后免疫磁分离（IMS）程序，已提高了苜蓿芽方法的灵敏度。但是，在这种琼脂培养基上，选择性琼脂板上的文化隔离仍然是一个挑战。这项研究的重点是减少竞争性菌群的水平并增强选择性琼脂上大肠杆菌O157：H7的分离。我们优化了富集后和富集后IMS珠的短酸处理方法。然后，在被大肠杆菌O157：H7人工污染的苜蓿芽中评估优化的酸处理。富集了0.2 cfu / g的紫花苜蓿芽5小时后，在对两种类型的IMS珠进行酸处理后，选择性板上的分离效果有了显着改善。富集了低水平污染的苜蓿芽后24小时，仅在不使用IMS或酸处理的情况下，才从8/25样品中回收了O157：H7大肠杆菌。仅使用酸处理可将回收率提高到19/25。在对浓缩肉汤进行IMS后，酸处理对Pathatrix（TM）的分离度提高到23/25，对于BeadRetriever（TM）IMS的分离度提高到24/25。对富集肉汤进行30分钟酸处理（pH 2）或对IMS珠进行7分钟处理是一种简单而又快速的方法，可通过减少选择性培养基上的干扰菌群来大大提高从苜蓿芽中富集的大肠杆菌0157的分离度。

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  • 来源
    《Food microbiology》 |2012年第1期|p.83-90|共8页
  • 作者

    Willis M. Fedio; Karen C. Jinneman; Ken J. Yoshitomi; Ruben Zapata; Stephen D. Weagant;

  • 作者单位

    New Mexico State University, Center for Animal Health, Food Safety and Biosecurity, Food Safety Laboratory, 2990 Knox Street, Las Cruces, NM 88003, United States;

    Food and Drug Administration, Pacific Regional Laboratory-Northwest, Bothell, WA, United States;

    Food and Drug Administration, Pacific Regional Laboratory-Northwest, Bothell, WA, United States;

    Weagant Consulting, Poulsbo, WA, United States;

    Weagant Consulting, Poulsbo, WA, United States;

  • 收录信息 美国《科学引文索引》(SCI);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    real-time PCR; immunomagnetic separation; escherichia coli O157:H7; acid treatment;

    机译：实时PCR;免疫磁分离大肠杆菌O157：H7;酸处理;

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