Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria.
Onderstepoort J Vet Res. 2022 Jul 27;89(1):e1-e10. doi: 10.4102/ojvr.v89i1.2021.
Detailed information on specific species of non-aureus staphylococci (NAS) has become a necessity for effective udder health control programs in South Africa. The main objective of this preliminary study was to identify the different NAS species and strains present in dairy herds in South Africa using a cost-effective method. A further objective was to investigate the effects of cow risk factors and farming systems on the NAS isolates identified. A total of 214 NAS, isolated from milk collected from 17 South African dairy herds, were identified using three diagnostic tests (API Staph test, MALDI-TOF and 16s rRNA). There was a good observed agreement between the MALDI-TOF and 16S rRNA sequencing (92.2%) and a poor observed agreement between the MALDI-TOF and API Staph (25.7%). The genetic relatedness within species was investigated in 128 of these isolates using random polymorphic amplified deoxyribonucleic acid (DNA) (RAPD), verified by multilocus sequence typing (MLST), and phylogenetic analysis and cow risk factors were investigated on species level. The main NAS species isolated were Staphylococcus chromogenes (75.2%), Staphylococcus epidermidis (9.4%) and Staphylococcus haemolyticus (8.9%). The RAPD test identified 34 Staphylococcus chromogenes, 13 Staphylococcus epidermidis and nine Staphylococcus haemolyticus strains, indicating genetic diversity amongst strains and herds. The presence of NAS intramammary infections was found to be significantly related to the farming systems, composite cow milk somatic cell count (SCC), parity and days in milk (DIM). Significantly more NAS were isolated from primiparous and from older cows. This knowledge could assist with the management of NAS on dairy farms.
详细的非金黄色葡萄球菌（NAS）物种信息对南非有效的乳房健康控制计划变得非常必要。本初步研究的主要目的是使用经济有效的方法来确定南非奶牛场中存在的不同 NAS 物种和菌株。另一个目的是研究奶牛风险因素和养殖系统对鉴定出的 NAS 分离株的影响。从 17 个南非奶牛场采集的牛奶中分离出 214 株 NAS，使用三种诊断测试（API Staph 测试、MALDI-TOF 和 16s rRNA）进行鉴定。MALDI-TOF 和 16S rRNA 测序（92.2%）之间观察到很好的一致性，而 MALDI-TOF 和 API Staph（25.7%）之间观察到一致性较差。对其中 128 株进行了种内遗传相关性研究，使用随机多态性扩增脱氧核糖核酸（DNA）（RAPD），通过多位点序列分型（MLST）和系统发育分析进行验证，并在种水平上调查了奶牛风险因素。分离的主要 NAS 物种为葡萄球菌（75.2%）、表皮葡萄球菌（9.4%）和溶血性葡萄球菌（8.9%）。RAPD 测试鉴定出 34 株葡萄球菌、13 株表皮葡萄球菌和 9 株溶血性葡萄球菌株，表明菌株和牛群之间存在遗传多样性。NAS 乳房内感染的存在与养殖系统、奶牛综合奶体细胞计数（SCC）、胎次和泌乳天数（DIM）显著相关。从初产牛和年龄较大的奶牛中分离出的 NAS 明显更多。这些知识可以协助管理奶牛场中的 NAS。
