Oliver Stephen P, Almeida Raul A, Gillespie Barbara E, Ivey Susan J, Moorehead Hugh, Lunn Phillip, Dowlen Henry H, Johnson David L, Lamar Ken C
Food Safety Center of Excellence, Department of Animal Science, Institute of Agriculture, The University of Tennessee, 2640 Morgan Circle, Knoxville, TN 37996, USA.
Vet Ther. 2003 Fall;4(3):299-308.
Streptococcus uberis is an important cause of mastitis in dairy cows throughout the world, particularly during the dry period, around the time of calving, and during early lactation. Strategies for controlling S. uberis mastitis have not received adequate research attention and are therefore poorly defined and inadequate. Objectives of the present study were to evaluate the efficacy of extended therapy regimens with pirlimycin for treatment of experimentally induced S. uberis intramammary infections in lactating dairy cows during early lactation and to evaluate the usefulness of the S. uberis experimental infection model for evaluating antimicrobial efficacy in dairy cows. The efficacy of extended pirlimycin intramammary therapy regimens was investigated in 103 mammary glands of 68 dairy cows that became infected following experimental challenge with S. uberis during early lactation. Cows infected with S. uberis in one or both experimentally challenged mammary glands were randomly allocated to three groups, representing three different treatment regimens with pirlimycin, including 2-day (n = 21 cows, 31 mammary quarters), 5-day (n = 21 cows, 32 quarters), and 8-day (n = 26 cows, 40 quarters). For all groups, pirlimycin was administered at a rate of 50 mg of pirlimycin hydrochloride via intramammary infusion. A cure was defined as an experimentally infected mammary gland that was treated with pirlimycin and was bacteriologically negative for the presence of S. uberis at 7, 14, 21, and 28 days after treatment. Experimental S. uberis intramammary infections were eliminated in 58.1% of the infected quarters treated with the pirlimycin 2-day regimen, 68.8% for the 5-day regimen, and 80.0% for the 8-day regimen. Significant differences (P <.05) in efficacy were observed between the 2-day and 8-day treatment regimens. The number of somatic cells in milk decreased significantly following therapy in quarters for which treatment was successful in eliminating S. uberis. However, there was no evidence to suggest that extended therapy with pirlimycin resulted in a greater reduction in somatic cell counts in milk than the 2-day treatment. The S. uberis experimental infection model was a rapid and effective means of evaluating antimicrobial efficacy during early lactation at a time when mammary glands are highly susceptible to S. uberis intramammary infection.
乳房链球菌是全球奶牛乳腺炎的重要病因，尤其是在干奶期、产犊前后以及泌乳早期。控制乳房链球菌乳腺炎的策略尚未得到充分的研究关注，因此定义不明确且不完善。本研究的目的是评估延长吡利霉素治疗方案对泌乳早期奶牛实验性诱导的乳房链球菌乳房内感染的治疗效果，并评估乳房链球菌实验感染模型在评估奶牛抗菌效果方面的实用性。在68头泌乳早期奶牛的103个乳房中，研究了延长吡利霉素乳房内治疗方案的疗效，这些奶牛在实验性感染乳房链球菌后被感染。在一个或两个实验性感染乳房中感染乳房链球菌的奶牛被随机分为三组，代表三种不同的吡利霉素治疗方案，包括2天（n = 21头奶牛，31个乳房象限）、5天（n = 21头奶牛，32个象限）和8天（n = 26头奶牛，40个象限）。对于所有组，通过乳房内灌注以50毫克盐酸吡利霉素的剂量给予吡利霉素。治愈定义为用吡利霉素治疗的实验性感染乳房，在治疗后7、14、21和28天乳房链球菌细菌学检测为阴性。用吡利霉素2天治疗方案治疗的感染象限中，58.1%的实验性乳房链球菌乳房内感染被消除，5天治疗方案为68.8%，8天治疗方案为80.0%。在2天和8天治疗方案之间观察到疗效有显著差异（P <.05）。对于成功消除乳房链球菌的象限，治疗后牛奶中的体细胞数量显著减少。然而，没有证据表明延长吡利霉素治疗比2天治疗能使牛奶中的体细胞计数有更大幅度的降低。乳房链球菌实验感染模型是在泌乳早期乳房对乳房链球菌乳房内感染高度易感时评估抗菌效果的快速有效方法。
