National Veterinary Institute, SE-75189 Uppsala, Sweden.
J Dairy Sci. 2010 Jan;93(1):180-91. doi: 10.3168/jds.2009-2471.
Staphylococcus aureus is a common udder pathogen of dairy cows that often causes herd problems. Various mastitis control programs have been used to combat the problem but have not always been efficient in preventing new Staph. aureus infections, indicating the presence of possible sources of infection other than those traditionally considered. Therefore, the aim of the study was to identify potential sources of infection relevant for Staph. aureus mastitis within 5 dairy herds with udder health problems caused by Staph. aureus. Samples were collected from milk of lactating cows, from body sites, and from the environment of lactating cows, dry cows, late pregnant heifers, young heifers 4 to 12 mo old, and heifer calves 0 to 3 mo old. Isolates of Staph. aureus were identified and compared using pulsed-field gel electrophoresis. Four to 7 unique Staph. aureus pulsotypes were found within each herd, with one strain predominating in milk in each herd. The milk pulsotypes were also frequently isolated in body samples, especially on hock skin, and in the immediate environment of lactating cows, and were sometimes found in other animal groups, especially in dry cows and heifer calves 0 to 3 mo old. The prevalence of Staph. aureus in milk and other types of samples varied markedly between herds. Staphylococcus aureus isolates with genotypes indistinguishable from those found in milk also dominated in extra-mammary sites within the dairy herds studied, and hock skin was identified as an important reservoir of Staph. aureus. The results contribute new knowledge necessary to improve strategies for udder health control in herds.
金黄色葡萄球菌是奶牛常见的乳房病原体，常引起牛群问题。已经使用了各种乳腺炎控制方案来解决这个问题，但在预防新的金黄色葡萄球菌感染方面并不总是有效，这表明可能存在除传统上认为的感染源以外的其他感染源。因此，本研究的目的是在 5 个乳房健康因金黄色葡萄球菌而出现问题的奶牛场中，确定与金黄色葡萄球菌乳腺炎相关的潜在感染源。从泌乳牛的牛奶、身体部位以及泌乳牛、干奶牛、妊娠后期小母牛、4 至 12 月龄小母牛和 0 至 3 月龄小母牛的环境中采集样本。使用脉冲场凝胶电泳对金黄色葡萄球菌分离株进行鉴定和比较。每个牛群中发现了 4 到 7 种独特的金黄色葡萄球菌脉冲型，每个牛群中都有一种优势菌株存在于牛奶中。在每个牛群中，奶脉冲型也经常在身体样本中分离出来，特别是在跗关节皮肤中，以及在泌乳牛的直接环境中，有时也在其他动物群体中发现，特别是在干奶牛和 0 至 3 月龄小母牛中。金黄色葡萄球菌在牛奶和其他类型样本中的流行率在牛群之间差异很大。在研究的奶牛场中，与在牛奶中发现的金黄色葡萄球菌基因型相同的金黄色葡萄球菌分离株也在乳腺外部位占主导地位，跗关节皮肤被确定为金黄色葡萄球菌的重要储存库。研究结果提供了必要的新知识，有助于改进牛群乳房健康控制策略。
