The first objective of this study was to determine whether differences would occur among teat end preparation techniques with regard to potential contamination of milk samples collected for bacterial culture. The second objective was to determine whether differences would be detected in genus or species of bacteria isolated from samples collected using the various methods as well as from contaminated or uncontaminated samples. Mammary quarter foremilk samples were collected from lactating dairy cattle at the University of Missouri Foremost Research Dairy Farm (Columbia). Four different teat end preparation methods were used to compare contamination rates in milk samples. Sampling techniques used before milk collection included (1) no preparation, (2) pre-milking disinfection and single-use towel drying of teats only, (3) scrubbing of the teat end with alcohol only, and (4) pre-milking disinfection, single-use towel drying, and scrubbing of the teat end with alcohol. Milk was plated on Columbia blood agar. Cultures were read at 48 h, with the number of morphologically different bacterial colony types quantified and isolated. Isolates were identified using MALDI-TOF mass spectrometry. Median numbers of colony types were compared among groups using Kruskal-Wallis ANOVA with post-hoc pairwise comparisons, and proportional data were compared using the chi-squared test. A total of 168 cows, including 665 quarters, were sampled, and 1,614 isolates resulted. Analysis with MALDI-TOF identified 29 unique genera and 81 unique species among the samples. More contaminated samples occurred in groups 1 and 2 compared with groups 3 and 4. Group 3 had more contaminated samples than group 4. The majority of Pseudomonas spp. isolates were identified within group 2. When applying previously described niches to Staphylococcus spp., environmental species were more likely to be identified among contaminated samples, whereas host-adapted species were more likely to be identified among uncontaminated samples. These data confirm that scrubbing the teat end with alcohol after pre-milking disinfection with an iodine-based teat disinfectant and drying of the teat minimizes contamination of the milk sample.

中文翻译：

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在收集用于奶牛细菌培养的牛奶样本之前，对4种不同的奶头消毒方法进行了评估。

这项研究的第一个目标是确定在奶头制备技术之间是否会因收集细菌培养的牛奶样品而受到污染。第二个目的是确定是否将从使用各种方法收集的样本以及受污染或未受污染的样本中分离出的细菌的属或物种中检测到差异。从密苏里大学最重要的研究奶牛场（哥伦比亚）的泌乳奶牛中收集四分之一乳腺前乳样品。四种不同的奶头制备方法用于比较牛奶样品中的污染率。收集牛奶之前使用的采样技术包括：（1）不做准备，（2）仅进行挤奶前消毒和一次性擦干奶嘴，（3）仅用酒精擦洗奶头，以及（4）预挤奶消毒，一次性毛巾擦干和用酒精擦洗奶头。将牛奶涂在哥伦比亚血琼脂上。在48小时读取培养物，定量并分离形态不同的细菌菌落类型的数量。使用MALDI-TOF质谱法鉴定分离物。使用Kruskal-Wallis ANOVA与事后成对比较比较各组之间的菌落类型中位数，并使用卡方检验比较比例数据。总共对168头奶牛（包括665个季度）进行了采样，并分离出1,614株。MALDI-TOF分析确定了样品中的29个独特属和81个独特物种。与第3和第4组相比，第1和第2组的污染样品更多。第3组比第4组污染的样本更多。大多数假单胞菌属。在第2组中鉴定出分离株。将上述生态位应用于葡萄球菌时，在受污染的样品中更有可能鉴定出环境物种，而在未受污染的样品中则有可能鉴定出适应宿主的物种。这些数据证实，在用基于碘的奶头消毒剂进行预挤奶消毒后，用酒精擦洗奶头，并将奶头干燥可以最大程度地减少牛奶样品的污染。而适应宿主的物种则更容易在未受污染的样品中被鉴定出来。这些数据证实，在用碘基奶头消毒剂进行预挤奶消毒后，用酒精擦洗奶头，并将奶头干燥可以最大程度地减少牛奶样品的污染。而适应宿主的物种则更容易在未受污染的样品中被鉴定出来。这些数据证实，在用碘基奶头消毒剂进行预挤奶消毒后，用酒精擦洗奶头，并将奶头干燥可以最大程度地减少牛奶样品的污染。