Evaluation of PCR detection of Salmonella in alfalfa sprouts and spent irrigation water collected during sprouting of naturally contaminated seed.
Evaluation of PCR detection of Salmonella in alfalfa sprouts and spent irrigation water collected during sprouting of naturally contaminated seed.
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DOI：
10.4315/0362-028x.jfp-12-155
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发表时间：
2013-02
影响因子：
2
通讯作者：
Nicole Maks;T. Fu
中科院分区：
文献类型：
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作者：
Nicole Maks;T. Fu
本研究评估了基于PCR的系统（杜邦Qualicon BAX）检测沙门氏菌在芽和用过的灌溉水收集在发芽的种子自然污染沙门氏菌的有效性。将拟南芥种子在梅森罐中在20和30°C下生长3天。通过最可能数（MPN）分析确定水和芽中存在的沙门氏菌水平。还测定了背景微生物群落水平。将用过的灌溉水和芽的样品在42°C下分别在连四硫酸盐肉汤和具有新生霉素的缓冲蛋白胨水中富集过夜，然后在BAX系统中运行。还根据美国食品和药物管理局的沙门氏菌细菌学分析手册（FDA BAM）方法富集样品作为比较。对于一些试验，与30°C相比，沙门氏菌水平在20°C下较低，并且背景微生物群落水平在20°C下为10（7）至10（8）CFU/g或ml，在30°C下为10（8）至10（9）CFU/g或ml。在沙门氏菌水平>1.1 MPN/g或ml的试验中，BAX和FDA BAM方法都能够在所有样品中检测到沙门氏菌。在沙门氏菌水平较低（0.21 MPN/g或ml或更低）的试验中，BAX能够检测到比FDA BAM更多的阳性样品。对于沙门氏菌<0.003 MPN/g或ml的一项试验，BAX或FDA BAM方法均未指示病原体的存在。结果表明，PCR检测到低水平的沙门氏菌的芽或用灌溉水收集发芽的自然污染的种子。
This study evaluated the efficacy of a PCR-based system (DuPont Qualicon BAX) for detection of Salmonella in sprouts and spent irrigation water collected during sprouting of seeds naturally contaminated with Salmonella. Alfalfa seeds were grown in Mason jars at 20 and 30°C for 3 days. Levels of Salmonella present in the water and sprouts were determined by most-probable-number (MPN) analysis. Background microflora levels were also determined. Samples of spent irrigation water and sprouts were enriched overnight individually in tetrathionate broth and in buffered peptone water with novobiocin at 42°C and then run in the BAX system. Samples were also enriched according to the U.S. Food and Drug Administration's Bacteriological Analytical Manual (FDA BAM) method for Salmonella as a comparison. Salmonella levels were lower at 20°C compared with 30°C for some trials, and background microflora levels ranged from 10(7) to 10(8) CFU/g or ml at 20°C and 10(8) to 10(9) CFU/g or ml at 30°C. In trials with a Salmonella level >1.1 MPN/g or ml, both the BAX and FDA BAM methods were able to detect Salmonella in all samples. In trials with lower levels (0.21 MPN/g or ml or lower) of Salmonella, BAX was able to detect more positive samples than FDA BAM. For one trial with <0.003 MPN/g or ml of Salmonella, the presence of the pathogen was not indicated by either the BAX or the FDA BAM method. The results suggest that PCR detected low levels of Salmonella in sprouts or spent irrigation water collected from sprouting of naturally contaminated seeds.