Lohuis J A, Kremer W, Schukken Y H, Smit J A, Verheijden J H, Brand A, Van Miert A S
College of Veterinary Medicine, University of Utrecht, The Netherlands.
J Dairy Sci. 1990 Jun;73(6):1508-14. doi: 10.3168/jds.S0022-0302(90)78818-2.
The objective of this study was to assess growth of Escherichia coli in milk from endotoxin-induced mastitic quarters and to relate the in vitro findings to the course of experimental E. coli mastitis. Whole and skim milks from 24 rear quarters of 12 cows were inoculated with E. coli 0:157 and incubated at 38 degrees C. Growth of E. coli 0:157 was not inhibited in milk collected from rear quarters immediately prior to endotoxin infusion. However, growth inhibition occurred in all but one whole mastitic milk samples collected from mastitic quarters 18 h after infusion of .1 mg of endotoxin. Skim milk samples from mastitic quarters were bactericidal in four cows (7 quarters), whereas growth occurred in skim mastitic milk from 17 quarters of nine cows. Rear quarters of all cows were inoculated with 10(4) cfu of E. coli 0:157 19 h after the quarters had been infused with endotoxin. Clinical parameters and milk production were monitored during 36 h and 21 d, respectively. None of the inoculated quarters developed signs of inflammation, and secreta from inoculated quarters were bacteriologically negative after 48 h. Therefore, growth-inhibitory property of skim milk from endotoxin-induced quarters was apparently not a suitable parameter to monitor differences in susceptibility to E. coli mastitis.
本研究的目的是评估内毒素诱导的患乳房炎奶牛乳房中大肠杆菌的生长情况，并将体外研究结果与实验性大肠杆菌乳房炎的病程相关联。从12头奶牛的24个后乳房采集全脂奶和脱脂奶，接种大肠杆菌O:157，并在38℃下孵育。在内毒素注入前立即从后乳房采集的牛奶中，大肠杆菌O:157的生长未受抑制。然而，在注入0.1mg内毒素18小时后，从患乳房炎的乳房采集的所有全脂患乳房炎奶样（除一份外）均出现生长抑制。来自患乳房炎乳房的脱脂奶样在4头奶牛（7个乳房）中具有杀菌作用，而来自9头奶牛17个乳房的脱脂患乳房炎奶样中出现了细菌生长。在所有奶牛的乳房注入内毒素19小时后，每个乳房接种10(4) cfu的大肠杆菌O:157。分别在36小时和21天内监测临床参数和产奶量。接种的乳房均未出现炎症迹象，接种乳房的分泌物在48小时后细菌学检测为阴性。因此，内毒素诱导的乳房产生的脱脂奶的生长抑制特性显然不是监测对大肠杆菌乳房炎易感性差异的合适参数。
