US Food and Drug Administration, Center for Food Safety and Applied Nutrition, College Park, MD 20740, United States.
Int J Food Microbiol. 2012 Jul 2;157(2):267-77. doi: 10.1016/j.ijfoodmicro.2012.05.019. Epub 2012 May 25.
Listeria monocytogenes is readily found in the environment of retail deli establishments and can occasionally contaminate food handled in these establishments. Here we synthesize the available scientific evidence to derive probability distributions and mathematical models of bacterial transfers between environmental surfaces and foods, including those during slicing of food, and of bacterial removal during cleaning and sanitizing (models available at www.foodrisk.org). Transfer coefficients varied considerably by surface type, and after log(10) transformation were best described by normal distributions with means ranging from -0.29 to -4.96 and standard deviations that ranged from 0.07 to 1.39. 'Transfer coefficients' during slicing were best described by a truncated logistic distribution with location 0.07 and scale 0.03. In the absence of protein residues, mean log inactivation indicated a greater than 5 log(10) reduction for sanitization with hypochlorite (mean: 6.5 log(10); 95% confidence interval (CI): 5.0-8.1 log(10)) and quaternary ammonium compounds (mean: 5.5 log(10); 95% CI: 3.6-7.3 log(10)), but in the presence of protein residues efficacy reduced dramatically for hypochlorite (mean: 3.8 log(10); 95% CI: 2.1-5.4 log(10)) as well as quaternary ammonium compounds (mean: 4.4log(10); 95% CI: 2.5-6.4 log(10)). Overall, transfer coefficients are therefore low, even though cross-contamination can be extremely efficient under certain conditions. Dozens of food items may consequently be contaminated from a single contaminated slicer blade, albeit at low concentrations. Correctly performed sanitizing efficiently reduces L. monocytogenes contamination in the environment and therefore limits cross-contamination, even though sanitization is only performed a few times per day. However, under unfavorable conditions reductions in bacterial concentration may be far below 5 log(10). The probability distributions and mathematical models derived here can be used to evaluate L. monocytogenes cross-contamination dynamics in environments where foods are handled, and to assess the potential impact of different intervention strategies.
单核细胞增生李斯特菌在零售熟食店环境中很容易发现，偶尔会污染这些场所处理的食品。在这里，我们综合了现有的科学证据，得出了细菌在环境表面和食品之间转移的概率分布和数学模型，包括在食品切片过程中的转移，以及在清洁和消毒过程中细菌的去除（可在 www.foodrisk.org 上获得模型）。转移系数因表面类型而异，经对数转换后，最好用平均值范围在-0.29 到-4.96 之间、标准差范围在 0.07 到 1.39 之间的正态分布来描述。切片过程中的“转移系数”最好用截断的逻辑分布来描述，位置为 0.07，比例为 0.03。在没有蛋白质残留物的情况下，平均对数失活表明，用次氯酸盐（平均值：6.5 对数（10）；95%置信区间（CI）：5.0-8.1 对数（10））和季铵化合物（平均值：5.5 对数（10）；95%CI：3.6-7.3 对数（10））进行消毒，可使细菌减少大于 5 对数（10），但在有蛋白质残留物的情况下，次氯酸盐（平均值：3.8 对数（10）；95%CI：2.1-5.4 对数（10））和季铵化合物（平均值：4.4 对数（10）；95%CI：2.5-6.4 对数（10））的杀菌效果显著降低。总体而言，转移系数较低，尽管在某些条件下，交叉污染可能非常有效。因此，即使浓度很低，从单个污染的切片刀片上也可能会污染数十种食品。正确执行的消毒可以有效地减少环境中的单核细胞增生李斯特菌污染，从而限制交叉污染，尽管每天只进行几次消毒。然而，在不利条件下，细菌浓度的降低可能远低于 5 对数（10）。这里得出的概率分布和数学模型可用于评估食品处理环境中单核细胞增生李斯特菌的交叉污染动态，并评估不同干预策略的潜在影响。
