Lindquist Danielle A, Baynes Ronald E, Smith Geof W
Department of Population Health and Pathobiology and the Food Animal Residue Avoidance Depletion Program, College of Veterinary Medicine, North Carolina State University, Raleigh 27607.
Department of Population Health and Pathobiology and the Food Animal Residue Avoidance Depletion Program, College of Veterinary Medicine, North Carolina State University, Raleigh 27607.
J Dairy Sci. 2015 Mar;98(3):1856-61. doi: 10.3168/jds.2014-8715. Epub 2014 Dec 26.
Mastitis remains a critical disease in the dairy industry and the use of intramammary antibiotics plays a critical role in mastitis treatment. Hetacillin is currently approved as an intramammary antibiotic that is used to treat mastitis in dairy cows. It is approved for once a day administration and can be used for a total of 3 d. An increasing number of dairy farms are milking 3 times per day (instead of the traditional 2 times per day) and very little pharmacokinetic data exists on the use of intramammary drugs in a 3×system. The primary purpose of this study was to determine if once a day intramammary infusion of hetacillin is sufficient to maintain therapeutic drug concentrations in cattle milked 3 times per day. Eight Holstein cattle milked 3 times per day were used in this study. After collecting a baseline milk sample, each cow received intramammary infusions of hetacillin in the left front and right rear quarters once a day for 3 d. Milk samples from each of the treated quarters were collected at each milking and frozen until analysis. Milk samples were analyzed for ampicillin concentrations using an ultra-performance liquid chromatography method. All treated quarters had antibiotic concentrations well above the minimum inhibitory concentration (MIC) for gram-positive mastitis pathogens at 8 and 16 h postinfusion. Milk concentrations had fallen well below the MIC by the 24-h period (before the next infusion). All 8 cows in this study consistently had individual quarter milk ampicillin concentrations below the FDA tolerance of 0.01 μg/mL (10 ppb) within 48 h of the last infusion. Based on this study, milk ampicillin concentrations exceed the minimum inhibitory concentration required to inhibit the growth of 90% of organisms (MIC90) for at least 65% of the dosing interval, which is sufficient for once-daily dosing with most cases of gram-positive mastitis. Therefore, intramammary hetacillin should be an effective treatment for the vast majority of gram-positive mastitis pathogens when used according to label (once per day) in cows milked 3 times per day.
乳腺炎仍是乳制品行业中的一种关键疾病，乳房内使用抗生素在乳腺炎治疗中起着关键作用。海他西林目前被批准作为一种乳房内使用的抗生素，用于治疗奶牛乳腺炎。它被批准每日给药一次，总共可使用3天。越来越多的奶牛场每天挤奶3次（而非传统的每天2次），而关于在每天挤奶3次的系统中使用乳房内药物的药代动力学数据非常少。本研究的主要目的是确定每天一次乳房内输注海他西林是否足以在每天挤奶3次的奶牛的牛奶中维持治疗药物浓度。本研究使用了8头每天挤奶3次的荷斯坦奶牛。在采集基线牛奶样本后，每头奶牛的左前乳房和右后乳房每天接受一次海他西林乳房内输注，持续3天。在每次挤奶时从每个处理过的乳房采集牛奶样本并冷冻直至分析。使用超高效液相色谱法分析牛奶样本中的氨苄西林浓度。所有处理过的乳房在输注后8小时和16小时的抗生素浓度均远高于革兰氏阳性乳腺炎病原体的最低抑菌浓度（MIC）。到24小时（在下一次输注前）时，牛奶浓度已大幅降至MIC以下。本研究中的所有8头奶牛在最后一次输注后的48小时内，各个乳房的牛奶氨苄西林浓度始终低于美国食品药品监督管理局（FDA）规定的0.01μg/mL（10 ppb）的耐受量。基于本研究，牛奶氨苄西林浓度在至少65%的给药间隔内超过抑制90%的微生物生长所需的最低抑菌浓度（MIC90），这对于大多数革兰氏阳性乳腺炎病例的每日一次给药来说是足够的。因此，当按照标签说明（每天一次）在每天挤奶3次的奶牛中使用时，乳房内注射海他西林应该是治疗绝大多数革兰氏阳性乳腺炎病原体的有效方法。
