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首页> 外文学位 >Prevalence and biological control of Salmonella contamination in rendering plant environments and the finished rendered meals.
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Prevalence and biological control of Salmonella contamination in rendering plant environments and the finished rendered meals.

机译：提炼工厂环境和成品提炼粉中沙门氏菌污染的发生率和生物学控制。

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摘要

The objectives of this study were to: (1) isolate and characterize Salmonella and enterococci from finished animal by-products, (2) produce and optimize a bacteriophage cocktail against Salmonella, (3) apply the bacteriophages to reduce Salmonella levels on environmental surfaces found in a rendering facility and in raw offal, and (4) use the bacteriophage as a feed additive to reduce or prevent Salmonella infection in mice.;To determine the prevalence of Salmonella and enterococci, two hundred finished meals provided by various rendering facilities across the U.S. were analyzed. While the animal meals were shown to not be a suitable environment for bacterial growth (moisture content 1.9 to 11.5%), these products did contain enterococci and Salmonella. Enterococci were detected in 83% of the samples and accounted for up to 54% of the total bacterial count, which ranged from 1.7 to 6.8 log CFU/g. Characterization of the enterococci isolates revealed that only 3 isolates were resistant to vancomycin (32 mug/ml).;As a means to prevent or reduce Salmonella contamination, bacteriophages were isolated from raw chicken offal that would be used for rendering. Bacteriophages were isolated by using the Salmonella spp. isolated previously from the finished meals as the host bacteria. For further study, five of the isolated bacteriophages (n = ?) were selected to produce a cocktail for bacteriophage treatment studies. The optimized bacteriophage cocktail was able to successfully reduce Salmonella levels on all tested environmental surfaces.;In addition to the surface materials, the bacteriophage cocktail was shown to reduce Salmonella levels in raw chicken offal. When treating irradiated raw offal that was artificially contaminated with the Salmonella cocktail (105 CFU/g), the bacteriophage cocktail reduced Salmonella levels by ca. 2.0, 2.7, and 2.5 log CFU/g at 20°, 30°, and 40°C, respectively. The bacteriophage was also capable of reducing Salmonella levels to the same degree, i.e., ca. 2.0, 2.2, and 2.2 log CFU/g at 20°, 30°, and 40°C, respectively, in the non-sterile raw chicken offal at the presence of background microorganisms.;The bacteriophage cocktail was also evaluated as a feed additive. The bacteriophage cocktail was lyophilized and added into the animal meals (blood, feather, and poultry), which were artificially contaminated with a five-strain Salmonella cocktail at initial level of ca. 105 CFU/g. A series of dehydration studies revealed that the addition of dehydrated bacteriophages to finished meals does not reduce the level of Salmonella present upon rehydration; however, there was an observable difference between those samples containing the bacteriophages and those that did not after 12 h of rehydration, with those containing the bacteriophages having lower levels of Salmonella (ca. 2 log CFU/g difference ??). Our results also revealed that the bacteriophage cocktail's stability was reduced quickly when applied in a dehydrated form.;The liquid bacteriophage was then supplemented into animal feed and given to mice during an animal trial. The mice that had been given a diet containing the bacteriophage for a period of a week prior to Salmonella inoculation were not infected as evidenced through fecal sampling. These mice shed no Salmonella in their feces over a 4 week period. Mice that had not been given the diet supplemented with the bacteriophage shed Salmonella in their feces for a period of 2.5 weeks. Histological analysis of the liver and intestine also indicated no observable signs of inflammation in those mice given the bacteriophages. In mice not receiving the bacteriophage treatment, venous dilation, cholangiohepatitis, and monocytes in the portal areas were observed in the liver.;Our results indicate that the Salmonella contamination of finished rendered meals is likely the source of cross-contamination between the environment or the incoming raw material and the finished products. The risk for cross-contamination may be reduced through the use of bacteriophage treatment which was found to reduce ca. 99 to 99.9% of Salmonella levels on both the environmental surfaces and raw material. The bacteriophage cocktail was also found to have the potential to be used as a feed additive to reduce pathogen levels within an animal host when added to the feed in liquid form just prior to consumption. (Abstract shortened by UMI.).
机译：这项研究的目的是：（1）从动物副产品中分离和鉴定沙门氏菌和肠球菌；（2）生产和优化针对沙门氏菌的噬菌体鸡尾酒；（3）应用噬菌体以降低发现的环境表面上的沙门氏菌水平。 （4）使用噬菌体作为饲料添加剂来减少或预防小鼠沙门氏菌的感染。为了确定沙门氏菌和肠球菌的患病率，整个猪舍的各种提炼设施提供了200顿最终膳食美国进行了分析。虽然动物饲料被证明不是细菌生长的合适环境（水分含量为1.9％至11.5％），但这些产品的确含有肠球菌和沙门氏菌。在83％的样品中检测到肠球菌，占细菌总数的54％，范围为1.7至6.8 log CFU / g。肠球菌分离株的特征表明，只有3个分离株对万古霉素具有抗药性（32杯/毫升）。作为预防或减少沙门氏菌污染的一种方法，从生鸡内脏中分离了噬菌体用于提纯。通过使用沙门氏菌属分离出噬菌体。从成品中分离出先前的宿主细菌。为了进一步研究，选择了五个分离的噬菌体（n =β）来生产用于噬菌体治疗研究的混合物。经过优化的噬菌体鸡尾酒能够成功降低所有测试环境表面上的沙门氏菌水平。除表面材料外，该噬菌体鸡尾酒还显示出可以降低生鸡肉内脏中的沙门氏菌水平。当处理被沙门氏菌鸡尾酒（105 CFU / g）人工污染的经辐照的生杂碎时，噬菌体鸡尾酒可使沙门氏菌水平降低约20％。在20°C，30°C和40°C时分别为2.0、2.7和2.5 log CFU / g。该噬菌体还能够将沙门氏菌水平降低至相同程度，即约。在有背景微生物存在的非无菌生鸡肉内脏中，分别在20°，30°和40°C下分别为2.0、2.2和2.2 log CFU / g。 。将噬菌体混合物冻干，并添加到动物餐（血液，羽毛和家禽）中，这些动物餐被五株沙门氏菌鸡尾酒人工污染，初始浓度约为5℃。 105 CFU /克。一系列的脱水研究表明，在完成的膳食中添加脱水的噬菌体并不能降低脱水后沙门氏菌的含量。然而，那些含有噬菌体的样品与那些在补液12小时后没有的样品之间存在可观察到的差异，而含有这些噬菌体的样品中沙门氏菌含量较低（约2 log CFU / g差Δε）。我们的结果还表明，以脱水形式使用时，噬菌体混合物的稳定性会迅速降低。;然后将液态噬菌体添加到动物饲料中，并在动物试验中给予小鼠。如通过粪便采样所证明的，在沙门氏菌接种之前一周饮食中含有噬菌体的小鼠没有被感染。这些小鼠在4周内未在粪便中流出沙门氏菌。未接受补充有噬菌体饮食的小鼠在其排泄物中排泄沙门氏菌达2.5周。肝和肠的组织学分析还表明，在给予噬菌体的那些小鼠中没有可观察到的炎症迹象。在未接受噬菌体治疗的小鼠中，在肝脏中观察到门静脉区域的静脉扩张，胆管肝炎和单核细胞。我们的结果表明，沙门氏菌对成品提炼食品的污染很可能是环境或食物之间交叉污染的来源。原材料和成品。可以通过使用噬菌体处理降低交叉污染的风险，发现这种处理可以降低ca。在环境表面和原材料上沙门氏菌水平的99％至99.9％。还发现，噬菌体混合物有潜力用作饲料添加剂，当在食用前以液体形式添加到饲料中时，可以降低动物宿主内的病原体水平。 （摘要由UMI缩短。）。

著录项

  • 作者

    Kinley, Brandon.;

  • 作者单位

    Clemson University.;

  • 授予单位 Clemson University.;
  • 学科 Biology Microbiology.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 184 p.
  • 总页数 184
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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