Reydams H, Toledo-Silva B, Mertens K, Piepers S, de Souza F N, Haesebrouck F, De Vliegher S
M-team and Mastitis and Milk Quality Research Unit, Department of Internal Medicine, Reproduction, and Population Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium.
M-team and Mastitis and Milk Quality Research Unit, Department of Internal Medicine, Reproduction, and Population Medicine, Faculty of Veterinary Medicine, Ghent University, 9820 Merelbeke, Belgium.
J Dairy Sci. 2023 Nov;106(11):7974-7990. doi: 10.3168/jds.2022-23092. Epub 2023 Aug 23.
Non-aureus staphylococci and the closely related mammaliicoccal species (NASM) are the most common causes of bovine subclinical mastitis on modern dairy farms and are highly prevalent in bulk-tank milk. The purpose of this study was to determine the distribution of NASM in both composite cow milk (CCM) and bulk-tank milk (BTM) samples collected in tandem in commercial Flemish dairy herds and to estimate the origin of the different (subgroups of) NASM species present in BTM by applying strain typing (random amplification of polymorphic DNA or random amplified DNA [RAPD]). A single cross-sectional sampling was performed over 5 herds that volunteered to participate in the study. Composite cow milk samples (n = 356) were collected from all lactating cows (except those with clinical mastitis) during a milking in tandem with 6 BTM samples per herd sequentially collected immediately post that milking (n = 30). In total, 421 and 80 NASM isolates were recovered and identified by MALDI-TOF mass spectrometry from the CCM and BTM samples, respectively and a total of 21 and 12 different NASM species were identified from CCM and BTM samples, respectively. Staphylococcus cohnii was the most prevalent NASM species found in BTM followed by Staphylococcus haemolyticus, Staphylococcus epidermidis, Mammaliicoccus lentus, and Staphylococcus equorum, whereas from CCM samples the most common species were S. hemolyticus, S. cohnii, S. equorum, S. epidermidis, and Staphylococcus chromogenes. The prevalent NASM species in both CCM and BTM samples was distinct for each herd, corroborating other studies observing a herd-specific NASM microbiota. Random amplified DNA analysis was performed on 9 NASM species (S. chromogenes, S. epidermidis, S. haemolyticus, S. equorum, Mammaliicoccus sciuri, Staphylococcus xylosus, S. cohnii, Staphylococcus debuckii, and M. lentus) because these species were isolated from both sample types in a herd. The same RAPD types were found in both sample types for all NASM species selected for strain typing in varying degrees. When assessing the distribution of NASM species, differences within NASM species should be examined meaning a closer look should be taken at the strain level rather than at the species level only.
非金黄色葡萄球菌和与之密切相关的哺乳动物葡萄球菌属（NASM）是现代奶牛场牛亚临床乳腺炎最常见的病因，且在储奶罐乳中高度流行。本研究的目的是确定在佛兰德商业奶牛群中同时采集的复合牛奶（CCM）和储奶罐乳（BTM）样本中NASM的分布情况，并通过应用菌株分型（随机扩增多态性DNA或随机扩增DNA [RAPD]）来估计BTM中存在的不同NASM物种（亚组）的来源。对自愿参与研究的5个牛群进行了单次横断面采样。在挤奶过程中，从所有泌乳奶牛（临床型乳腺炎奶牛除外）采集复合牛奶样本（n = 356），并在该次挤奶后立即依次从每个牛群中采集6份BTM样本（n = 30）。通过基质辅助激光解吸电离飞行时间质谱法，分别从CCM和BTM样本中总共分离并鉴定出421株和80株NASM菌株，并且分别从CCM和BTM样本中总共鉴定出21种和12种不同的NASM物种。科氏葡萄球菌是在BTM中发现的最常见的NASM物种，其次是溶血葡萄球菌、表皮葡萄球菌、缓慢哺乳动物葡萄球菌和马胃葡萄球菌，而在CCM样本中最常见的物种是溶血葡萄球菌、科氏葡萄球菌、马胃葡萄球菌、表皮葡萄球菌和产色葡萄球菌。每个牛群的CCM和BTM样本中流行的NASM物种都不同，这证实了其他观察到牛群特异性NASM微生物群的研究。对9种NASM物种（产色葡萄球菌、表皮葡萄球菌、溶血葡萄球菌、马胃葡萄球菌、松鼠哺乳动物葡萄球菌、木糖葡萄球菌、科氏葡萄球菌、德布氏葡萄球菌和缓慢哺乳动物葡萄球菌）进行了随机扩增DNA分析，因为这些物种在一个牛群的两种样本类型中均有分离。对于所有选择进行菌株分型的NASM物种，在两种样本类型中均不同程度地发现了相同的RAPD类型。在评估NASM物种的分布时，应检查NASM物种内部的差异，这意味着应在菌株水平而非仅在物种水平上进行更仔细的观察。
