毒力基因谱：中国奶牛临床型乳房炎金黄色葡萄球菌分离株中的α-溶血素与克隆多样性
Virulence gene profiles: alpha-hemolysin and clonal diversity in Staphylococcus aureus isolates from bovine clinical mastitis in China.
作者信息
Zhang Limei, Gao Jian, Barkema Herman W, Ali Tariq, Liu Gang, Deng Youtian, Naushad Sohail, Kastelic John P, Han Bo
机构信息
College of Veterinary Medicine, China Agricultural University, Yuan Ming Yuan West Road No. 2, Haidian District, Beijing, 100193, People's Republic of China.
Department of Production Animal Health, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, T2N 4N1, Canada.
出版信息
BMC Vet Res. 2018 Mar 2;14(1):63. doi: 10.1186/s12917-018-1374-7.
BACKGROUND
Staphylococcus aureus, a common cause of bovine mastitis, is known for its ability to acquire to antimicrobial resistance and to secrete numerous virulence factors that can exacerbate inflammation. In addition, alpha-hemolysin has an important role in S. aureus infections, diversity of the hla gene (that produces alpha-hmolysin) in S. aureus isolated from bovine mastitis has not been well characterized. The objective was, therefore, to determine diversity of virulence genes, hla gene sequences, and clonal profiles of S. aureus from bovine mastitis in Chinese dairy herds, and to evaluate inter-relationships.
RESULTS
The antimicrobials resistance varies from as low as 1.9% (2/103) for CTX to as high as 76.7% (79/103) for penicilin in the 103 isolates and 46 (44.7%) S. aureus were determined as multi-resistant isolates with diverse resistance patterns. Thirty-eight virulence gene patterns (with variable frequencies) were identified in the 103 isolates and correlated with MLST types, indicating a great diversity. Although the hla gene also had great diversity (14 genotypes), Hla peptides were relatively more conserved. With 7 clonal complexes identified from 24 spa types and 7 MLST types. Regarding the letter, ST 97 was the dominant type in S. aureus from bovine mastitis in China. Furthermore, based on phylogenetic analysis, there was a distinct evolutionary relationship between the hla gene and MLST.
CONCLUSION
Multi-resistant S. aureus occurred in bovine mastitis with diverse resistance patterns. The diversity of virulence gene profiles, especially the hla gene and, their relationship with molecular types were reported for the first time in S. aureus from bovine mastitis, which will be useful for future studies on immunogenicity and vaccine development. In addition, based on the distinct evolutionary relationship between the hla gene and MLST types, we inferred that the hla gene has potential role for molecular typing of S. aureus.
背景
金黄色葡萄球菌是牛乳腺炎的常见病因，以其获得抗菌药物耐药性的能力以及分泌多种可加剧炎症的毒力因子而闻名。此外，α-溶血素在金黄色葡萄球菌感染中起重要作用，但从牛乳腺炎分离出的金黄色葡萄球菌中hla基因（产生α-溶血素）的多样性尚未得到充分表征。因此，本研究的目的是确定中国奶牛场牛乳腺炎金黄色葡萄球菌的毒力基因多样性、hla基因序列和克隆型，并评估它们之间的相互关系。
结果
103株分离株的抗菌药物耐药率差异较大，CTX的耐药率低至1.9%（2/103），青霉素的耐药率高达76.7%（79/103），46株（44.7%）金黄色葡萄球菌被确定为具有多种耐药模式的多重耐药菌株。在103株分离株中鉴定出38种毒力基因模式（频率各异），并与多位点序列分型（MLST）类型相关，表明具有高度多样性。虽然hla基因也具有高度多样性（14种基因型），但Hla肽相对较为保守。从24种spa分型和7种MLST类型中鉴定出7个克隆复合体。就后者而言，ST97是中国牛乳腺炎金黄色葡萄球菌中的优势类型。此外，基于系统发育分析，hla基因与MLST之间存在明显的进化关系。
结论
牛乳腺炎中存在具有多种耐药模式的多重耐药金黄色葡萄球菌。首次报道了牛乳腺炎金黄色葡萄球菌中毒力基因谱的多样性，尤其是hla基因及其与分子类型的关系，这将有助于未来关于免疫原性和疫苗开发的研究。此外，基于hla基因与MLST类型之间明显的进化关系，我们推断hla基因在金黄色葡萄球菌的分子分型中具有潜在作用。
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