Abstract: In this study，two suspected Streptococcus strains were isolated from tissue samples（heart and lung） of diseased pigs collected from two large?scale pig farms in Shaoguan and Guangzhou，designated as GDsg-2026 and GDgz- 2026，respectively. The isolated were subjected to systematic characterization，including morphological observation，biochemical identification，sequencing of the 16S rRNA and glyS gene，and antimicrobial susceptibility testing. Both strains exhibited alpha?hemolysis on blood agar plates and appeared as Gram?positive cocci in chains under microscopic examination. Their biochemical profiles were consistent with those of Streptococcus pluranimalium. Analysis of the 16S rRNA gene sequences revealed 99.5%－ 99.9% homology with S.pluranimalium strains derived from pig（MH329626），cattle（ON561146），goat（ON715886），chicken（MN023013），and camel（ON561146）in the GenBank database. Among these，GDsg?2026 was most closely related to pig?derived strains，whereas GDgz?2026 showed the closest relationship to bovine and camel?derived strains. The glyS gene sequences exhibited 97.7%－ 100.0% homology with previously reported bovine（CP025536）and porcine（CP078544）isolates，albeit with certain genetic distance variations. Antimicrobial susceptibility testing demonstrated that both strains were highly susceptible to enrofloxacin， cefazolin， cefradine， and cefoperazone， but showed significant resistance to lincomycin， tetracycline，trimethoprim，erythromycin，kanamycin，neomycin sulfate，and bacitracin. This study provides a valuable theoretical basis for the etiological characterization and epidemiological investigation of porcine?derived S. pluranimalium.

Key words: Streptococcus pluranimalium；Isolation and identification；Antibiotic resistance

摘要： 该研究从韶关和广州2个规模化猪场送检的病猪心脏、肺脏等组织样品中分离获得 2株疑似链球菌菌株，分别命名为GDsg?2026株和GDgz?2026株。对分离菌株进行了系统分 析，包括形态学观察、生化鉴定、16S rRNA及glyS 基因测序和药物敏感性试验。结果表明：2株 菌在血平板上均呈现α?型溶血，镜检为革兰阳性球菌，呈典型链状排列；其生化特征与多动物 链球菌（Streptococcus pluranimalium）相符。16S rRNA基因序列分析显示，分离株与GenBank数 据库中猪（MH329626）、牛（ON561146）、山羊（ON715886）、鸡（MN023013）和骆驼（ON561146）等 多动物链球菌分离株的同源性为99.5%－99.9%，其中GDsg?2026株与猪源菌株亲缘关系最 近，GDgz?2026株则与牛和骆驼源菌株亲缘关系最近；glyS 基因序列与GenBank数据库中已报 道的牛（CP025536）、猪（CP078544）分离株同源性为97.7%－100.0%，其亲缘关系存在一定的差 异。药敏试验显示2株多动物链球菌对恩诺沙星、头孢唑林、头孢拉定和头孢哌酮等高度敏感； 对林可霉素、四环素、甲氧苄啶、红霉素、卡那霉素、硫酸新霉素和杆菌肽产生严重耐药性。该 研究为猪源S.pluranimalium 的病原学特征、流行病学调查提供了参考依据。

关键词: 多动物链球菌；分离鉴定；药敏试验