Livestock and Fishery Research Center, Arba Minch University, P.O.BOX: 21, Arba Minch, Ethiopia.
Department of Pathobiology, College of Veterinary Medicine and Animal Science, University of Gondar, Gondar, Ethiopia.
BMC Microbiol. 2024 Jul 18;24(1):263. doi: 10.1186/s12866-024-03415-0.
Coagulase-negative Staphylococcus species are an emerging cause of intramammary infection, posing a significant economic and public health threat. The aim of this study was to assess the occurrence of coagulase-negative Staphylococcus species in bovine milk and dairy farms in Northwestern Ethiopia and to provide information about their antibiotic susceptibility and virulence gene profiles.
The cross-sectional study was conducted from February to August 2022. Coagulase-negative Staphylococcus species were isolated from 290 milk samples. Species isolation and identification were performed by plate culturing and biochemical tests and the antimicrobial susceptibility pattern of each isolate was determined by the Kirby-Bauer disc diffusion test. The single-plex PCR was used to detect the presence of virulent genes. The STATA software version 16 was used for data analysis. The prevalence, proportion of antimicrobial resistance and the number of virulent genes detected from coagulase-negative Staphylococcus species were analyzed using descriptive statistics.
Coagulase-negative Staphylococcus species were isolated in 28.6%, (95% CI: 23.5-34.2) of the samples. Of these, the S. epidermidis, S. sciuri, S. warneri, S. haemolyticus, S. simulans, S. chromogens, S. cohnii, and S. captis species were isolated at the rates of 11, 5.2, 3.4, 3.1, 3.1, 1, 1, and 0.7% respectively. All the isolates showed a high percentage (100%) of resistance to Amoxicillin, Ampicillin, and Cefotetan and 37.5% of resistance to Oxacillin. The majority (54.2%) of coagulase-negative isolates also showed multidrug resistance. Coagulase-negative Staphylococcus species carried the icaD, pvl, mecA, hlb, sec, and hla virulent genes at the rates of 26.5%, 22.1%, 21.7%, 9.6%, 9.6% and 8.4% respectively.
The present study revealed that the majority of the isolates (54.2%) were found multidrug-resistant and carriage of one or more virulent and enterotoxin genes responsible for intramammary and food poisoning infections. Thus, urgent disease control and prevention measures are warranted to reduce the deleterious impact of coagulase-negative species. To the best of our knowledge, this is the first study in Ethiopia to detect coagulase-negative Staphylococcus species with their associated virulent and food poisoning genes from bovine milk.
凝固酶阴性葡萄球菌是一种新兴的乳腺炎病原体，对经济和公共卫生构成重大威胁。本研究旨在评估凝固酶阴性葡萄球菌在埃塞俄比亚西北部奶牛场牛奶中的发生情况，并提供有关其抗生素敏感性和毒力基因谱的信息。
本横断面研究于 2022 年 2 月至 8 月进行。从 290 份牛奶样本中分离出凝固酶阴性葡萄球菌。通过平板培养和生化试验进行菌种分离和鉴定，采用 Kirby-Bauer 纸片扩散法测定各分离株的药敏模式。采用单重 PCR 检测毒力基因的存在。采用 STATA 软件 16 版进行数据分析。采用描述性统计方法分析凝固酶阴性葡萄球菌的流行率、抗生素耐药比例和检测到的毒力基因数量。
在 28.6%（95%CI：23.5-34.2）的样本中分离出凝固酶阴性葡萄球菌。其中，表皮葡萄球菌、松鼠葡萄球菌、华纳葡萄球菌、溶血葡萄球菌、模拟葡萄球菌、色素葡萄球菌、科氏葡萄球菌和卡皮斯葡萄球菌的分离率分别为 11%、5.2%、3.4%、3.1%、3.1%、1%、1%和 0.7%。所有分离株对阿莫西林、氨苄西林和头孢替坦的耐药率均为 100%，对苯唑西林的耐药率为 37.5%。大多数（54.2%）凝固酶阴性分离株也表现出多药耐药性。凝固酶阴性葡萄球菌携带 icaD、pvl、mecA、hlb、sec 和 hla 毒力基因的比例分别为 26.5%、22.1%、21.7%、9.6%、9.6%和 8.4%。
本研究表明，大多数分离株（54.2%）为多药耐药株，携带一个或多个与乳腺炎和食物中毒感染有关的毒力和肠毒素基因。因此，需要采取紧急疾病控制和预防措施，以降低凝固酶阴性菌的有害影响。据我们所知，这是埃塞俄比亚首次从奶牛牛奶中检测到凝固酶阴性葡萄球菌及其相关毒力和食物中毒基因。
