Negatively controlled, randomized clinical trial comparing different antimicrobial interventions for treatment of clinical mastitis caused by gram-positive pathogens

作者：Tiago Tomazi, M. Sumnicht, A.C.C.H. Tomazi, J.C.C. Silva, L. Bringhenti, Leticia Duarte, M.M.M. Silva, Marjory Xavier Rodrigues, R.C. Bicalho · 发表于：Journal of Dairy Science · 年份：2020 · DOI：10.3168/jds.2020-18830 · 被引用次数：19 · 研究领域：Milk Quality and Mastitis in Dairy Cows、Probiotics and Fermented Foods、Animal Genetics and Reproduction

The general objective of this study was to evaluate the effect of 3 intramammary antibiotic interventions using 2 commercially available antibiotics with narrow- or broad-spectrum activity on cure rates of clinical mastitis (CM) caused by gram-positive bacteria. We also compared the efficacy of treatment protocols, including a negative control, on outcomes at the cow and mammary quarter level. Before the onset of the study, 5,987 animals more than 12 mo old were randomly preassigned to 1 of 4 protocols in the event of gram-positive CM (except for Staphylococcus aureus and Trueperella pyogenes) during lactation: 3 infusions with 62.5 mg of amoxicillin performed 12 h apart (AMOX-L); 5 infusions once a day with 62.5 mg of amoxicillin (AMOX-EL); 5 infusions once a day with 125 mg of ceftiofur hydrochloride (CEFT-L); or negative control, no treatment performed until 5 d after diagnosis (NEG-CTR). Randomization was performed to preassign 90% of cows to one of the antibiotic protocols (30% in each group) and 10% to the negative control. A total of 696 quarter cases of CM met the inclusion criteria and were evaluated in the study. Quarter-level outcomes were assessed based on 5 milk samples collected up to 14 ± 3 d following enrollment (i.e., first day of treatment), whereas variables at the cow level [composite somatic cell count (SCC), milk production, and survival in the herd] were assessed up to 90 d after CM diagnosis. Streptococcus uberis, followed by Streptococcus dysgalactiae...