Clinic for Ruminants, Vetsuisse-Faculty, University of Bern, 3012 Bern, Switzerland; Institute of Microbiology, Department of Environment, Constructions and Design, University of Applied Sciences of Southern Switzerland (SUPSI), 6850 Mendrisio, Switzerland.
Repubblica e Cantone Ticino, Ufficio del Veterinario Cantonale, 6500 Bellinzona, Switzerland.
J Dairy Sci. 2024 Oct;107(10):8299-8312. doi: 10.3168/jds.2023-24245. Epub 2024 May 23.
The present study demonstrates successful herd sanitation and eradication of contagious mastitis caused by Staphylococcus aureus genotype B (GTB) in an entire Swiss district (Ticino) including 3,364 dairy cows from 168 farms. Herd sanitation included testing of all cows using a highly GTB-specific and sensitive real-time quantitative PCR (qPCR) assay, implementation of related on-farm measures, appropriate antibiotic therapy of GTB-positive cows, and culling of therapy-resistant animals, respectively. A treatment index was used as an objective criterion to select GTB-positive cows eligible for culling and replacement payment. Sixty-two herds (37%) were initially GTB-positive with a cow prevalence between 10% and 100% and were submitted to sanitation. Twenty months after the start of the campaign, all of these herds were free from S. aureus GTB, whereby 73% of them were sanitized during the first 7 mo. At the cow level, a total of 343 animals were infected. Fifty of them were immediately culled and farmers were financially compensated based on their treatment index value The remaining 293 cows were intramammarily treated with antibiotics either during lactation using the combination of cephalexin-kanamycin or penicillin-gentamicin or at dry-off using cloxacillin. Out of these cows, 275 (93.9%) were treated successfully, meaning that their milk was twice GTB-negative by qPCR after therapy. For lactational treatment, control samples were taken ≥10 and ≥20 d after treatment, for dry-off treatment ≥14 and ≥24 d after parturition. Neither lactation number nor SCC before treatment of the cow nor the type of therapy was associated with therapeutic cure. Using data of 30 GTB-positive and 71 GTB-negative herds (1,855 observations), the effect of GTB sanitation on bulk tank milk SCC (BTSCC) was evaluated by applying a linear mixed statistical model. In the year before sanitation, BTSCC was always higher in GTB-positive than in GTB-negative herds. After the start of the campaign, BTSCC declined rapidly in the herds under GTB sanitation and achieved values that no longer differed statistically from those of GTB-free herds after only 2 mo, remaining very similar for the rest of the campaign. The farmers were very satisfied with the outcome of the campaign because all GTB-positive herds could be sanitized rapidly, sanitation was sustainable, and milk quality increased.
本研究成功地对瑞士提契诺地区（Ticino）的整个地区（包括 168 个农场的 3364 头奶牛）进行了传染性乳腺炎的畜群卫生和根除，这些乳腺炎是由金黄色葡萄球菌基因型 B（GTB）引起的。畜群卫生包括使用高度针对 GTB 的敏感实时定量 PCR（qPCR）检测对所有奶牛进行检测、实施相关的农场措施、对 GTB 阳性奶牛进行适当的抗生素治疗以及分别淘汰治疗耐药动物。治疗指数被用作选择符合淘汰和替代支付条件的 GTB 阳性奶牛的客观标准。最初有 62 个畜群（37%）为 GTB 阳性，奶牛的患病率在 10%至 100%之间，它们都接受了卫生处理。在该活动开始后 20 个月，所有这些畜群均未检出金黄色葡萄球菌 GTB，其中 73%的畜群在头 7 个月内完成了卫生处理。在奶牛层面上，共有 343 头动物受到感染。其中 50 头立即被淘汰，农民根据他们的治疗指数值获得了经济补偿。其余 293 头奶牛在哺乳期使用头孢氨苄-卡那霉素或青霉素-庆大霉素组合或在干奶期使用氯唑西林进行了乳房内治疗。在这些奶牛中，有 275 头（93.9%）治疗成功，这意味着它们的牛奶在治疗后通过 qPCR 两次呈 GTB 阴性。对于哺乳期治疗，在治疗后≥10 天和≥20 天采集对照样本，对于干奶期治疗，在分娩后≥14 天和≥24 天采集对照样本。奶牛治疗前的泌乳次数或 SCC 或治疗类型均与治疗效果无关。使用 30 个 GTB 阳性和 71 个 GTB 阴性畜群（1855 个观察值）的数据，通过应用线性混合统计模型评估了 GTB 卫生对批量奶 SCC（BTSCC）的影响。在卫生处理前的一年中，GTB 阳性畜群的 BTSCC 始终高于 GTB 阴性畜群。在活动开始后，GTB 卫生处理的畜群中 BTSCC 迅速下降，仅在 2 个月后，BTSCC 就达到了与无 GTB 畜群不再具有统计学差异的值，并且在活动的其余时间内保持非常相似。农民对活动的结果非常满意，因为所有 GTB 阳性畜群都可以迅速进行卫生处理，卫生处理可持续，并且牛奶质量提高。
