Pyörälä S, Kaartinen L, Käck H, Rainio V
College of Veterinary Medicine, Department of Clinical Veterinary Medicine, Hautjärvi, Finland.
J Dairy Sci. 1994 Feb;77(2):453-61. doi: 10.3168/jds.S0022-0302(94)76973-3.
The objective of the study was to monitor the effect of two therapy regimens on experimental Escherichia coli mastitis. Single udder quarters of 12 cows that were at least 30 d postpartum were inoculated with 1500 cfu of E. coli. The inoculation was repeated in the contralateral quarter after a 3- to 4-wk interval. Initially, half of the cows were treated with antimicrobials, and the remaining half were left untreated. At the second inoculation, the cows that were originally treated were not treated, and vice versa. Therapy began 12 h after inoculation and consisted of parenteral trimethoprim-sulfadiazine (6 cows) or intramammary colistin sulfate (6 cows). Clinical signs, daily milk yield, bacterial count, and endotoxin content of the milk were recorded. Milk SCC, NAGase activity, and trypsin inhibitor capacity were also monitored. The response to bacterial challenge varied greatly among cows. Bacteria were eliminated from the quarters within 7 d in all but 1 cow. Treatment did not significantly affect the elimination rate of bacteria or any of the measured parameters. Significant positive correlations existed among milk bacterial counts, endotoxin concentrations, and clinical signs at the acute stage of the infection. Based on these findings, antimicrobial therapy of E. coli mastitis during lactation apparently is no more beneficial than no treatment.
本研究的目的是监测两种治疗方案对实验性大肠杆菌乳腺炎的效果。对12头产后至少30天的奶牛的单个乳房象限接种1500 cfu的大肠杆菌。在3至4周的间隔后，对侧象限重复接种。最初，一半的奶牛用抗菌药物治疗，其余一半不治疗。在第二次接种时，原来接受治疗的奶牛不再治疗，反之亦然。接种后12小时开始治疗，治疗方式为肌肉注射甲氧苄啶 - 磺胺嘧啶（6头奶牛）或乳房内注射硫酸黏菌素（6头奶牛）。记录临床症状、每日产奶量、细菌计数和牛奶中的内毒素含量。还监测了牛奶体细胞计数、N - 乙酰 - β - D - 氨基葡萄糖苷酶活性和胰蛋白酶抑制剂能力。奶牛对细菌攻击的反应差异很大。除1头奶牛外，所有奶牛乳房象限内的细菌在7天内被清除。治疗对细菌清除率或任何测量参数均无显著影响。在感染急性期，牛奶细菌计数、内毒素浓度和临床症状之间存在显著的正相关。基于这些发现，哺乳期大肠杆菌乳腺炎的抗菌治疗显然并不比不治疗更有益。
