Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames 50011.
Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames 50011.
J Dairy Sci. 2018 Nov;101(11):10398-10408. doi: 10.3168/jds.2017-14267. Epub 2018 Sep 7.
Clinical mastitis caused by Klebsiella spp. is an emerging problem in the US dairy industry and results in a high degree of financial losses to dairy workers. This study was conducted as a randomized, blinded, and placebo-controlled efficacy study of a Klebsiella pneumoniae siderophore receptor protein (SRP) vaccine (Kleb-SRP), with a total of 569 cows and heifers enrolled. The study was designed to look at vaccine effect on Klebsiella mastitis; however, the SRP in Klebsiella are highly conserved across coliform bacteria, which means that the vaccine has potential for cross-protection against all coliforms. Cows were paired based on parity, days in milk at enrollment, and somatic cell count. Within pairs, individuals were randomized to receive either Kleb-SRP or a placebo formulation. Following vaccination, the incidence of Klebsiella spp. and total coliform mastitis from natural exposure were compared to determine the efficacy of the vaccine. When analyzing all cows, the reduction of mastitis risk was not significant, though milk production increased 0.31 kg/d and somatic cell counts were reduced by 20.1%. When administered before calving, the vaccine reduced the risk of Klebsiella and total coliform mastitis by 76.9 and 47.5% respectively; however, we observed no significant effect when administered after calving. The vaccine, when administered before calving, also increased milk production by an average of 1.74 kg/d and reduced somatic cell counts by 64.8%. When administered after calving, we noted a slight decrease in daily milk production (0.39 kg) but no significant effect on somatic cell counts. All cows in the study (including vaccinates and placebo) received multiple doses of a commercially available licensed Escherichia coli bacterin. It should be noted that this herd was chosen because of the high number of clinical Klebsiella clinical mastitis cases this herd experienced before the trial and the extreme environmental challenge that was present from bedding with dried manure solids. The data from this study demonstrate efficacy of the Kleb-SRP vaccine against Klebsiella mastitis alone and coliform mastitis in general (including all coliforms) when administered before the initiation of a lactation cycle.
由克雷伯氏菌引起的临床乳腺炎是美国奶业的一个新出现的问题，给奶农造成了很高的经济损失。本研究是一项随机、双盲、安慰剂对照的肺炎克雷伯菌铁载体受体蛋白（SRP）疫苗（Kleb-SRP）的疗效研究，共纳入 569 头奶牛和小母牛。该研究旨在研究疫苗对克雷伯氏菌乳腺炎的作用；然而，克雷伯氏菌中的 SRP 在肠杆菌科细菌中高度保守，这意味着该疫苗有可能对所有肠杆菌科细菌产生交叉保护作用。奶牛根据胎次、入组时的泌乳天数和体细胞计数进行配对。在每对中，个体随机接受 Kleb-SRP 或安慰剂制剂。接种疫苗后，比较自然暴露引起的克雷伯氏菌和总大肠菌群乳腺炎的发生率，以确定疫苗的疗效。对所有奶牛进行分析时，乳腺炎风险的降低并不显著，但产奶量增加了 0.31 公斤/天，体细胞计数减少了 20.1%。在分娩前给药时，疫苗分别降低了克雷伯氏菌和总大肠菌群乳腺炎的风险 76.9%和 47.5%；然而，在分娩后给药时，我们没有观察到显著的效果。疫苗在分娩前给药还使产奶量平均增加 1.74 公斤/天，体细胞计数减少 64.8%。在分娩后给药时，我们注意到每日产奶量略有下降（0.39 公斤），但对体细胞计数没有显著影响。研究中的所有奶牛（包括接种疫苗和安慰剂）都接受了多次商业上可获得的许可大肠杆菌菌苗。应该指出的是，选择这个牛群是因为在试验前，这个牛群经历了大量的临床克雷伯氏菌乳腺炎病例，而且存在垫料中含有干燥粪便固体的极端环境挑战。本研究的数据表明，Kleb-SRP 疫苗在泌乳周期开始前使用时，对克雷伯氏菌乳腺炎和一般（包括所有肠杆菌科细菌）大肠菌群乳腺炎具有疗效。
