Resin acids are valued in traditional medicine for their antiseptic properties. Among these, abietic acid has been reported to be active against methicillin-resistant Staphylococcus aureus (MRSA) strains. In veterinary healthcare, the methicillin-resistant Staphylococcus pseudintermedius (MRSP) strain is an important reservoir of antibiotic resistance genes including mecA. The incidence of MRSP has been increasing, and treatment options in veterinary medicine are partial. Here, we investigated the antimicrobial and antibiofilm properties of abietic acid against three MRSP and two methicillin-susceptible Staphylococcus pseudintermedius (MSSP) strains, isolated from diseased pet animals and human wound samples. Abietic acid showed a significant minimal inhibitory concentration (MIC) value ranging from 32 to 64 μg/mL (MRSPs) and 8 μg/mL (MSSP). By checkerboard method we demonstrated that abietic acid increased oxacillin susceptibility of MRSP strains, thus showing a synergistic interaction with oxacillin. Abietic acid was also able to contrast the vitality of treated MSSP and MRSP1 biofilms at 20 μg/mL and 40 μg/mL, respectively. Finally, the compound moderately reduced mecA, mecR1 and mec1 gene expression. In conclusion, the results here reported demonstrate the antimicrobial activity of abietic acid against MRSP and support the use of this compound as a potential therapeutic agent to be used in combinatorial antibiotic therapy.

中文翻译：

---

松果酸与奥沙西林对耐甲氧西林假单胞菌的协同作用

树脂酸因其防腐性能而在传统医学中受到重视。其中，松香酸据报道对耐甲氧西林的金黄色葡萄球菌（MRSA）菌株具有活性。在兽医保健中，耐甲氧西林的伪中间葡萄球菌（MRSP）菌株是重要的抗生素抗性基因库，包括mecA。MRSP的发病率一直在增加，兽医学中的治疗选择是不完整的。在这里，我们研究了松香酸对三种MRSP和两种对甲氧西林敏感的金黄色葡萄球菌的抗菌和生物膜特性。（MSSP）菌株，从有病的宠物和人类伤口样本中分离出来。枞酸显示出显着的最小抑菌浓度（MIC）值，范围从32至64μg/ mL（MRSPs）和8μg/ mL（MSSP）。通过棋盘法，我们证明松香酸增加了MRSP菌株对奥沙西林的敏感性，因此显示了与奥沙西林的协同相互作用。松果酸还能够对比分别以20μg/ mL和40μg/ mL处理的MSSP和MRSP1生物膜的活力。最后，该化合物适度还原了mecA，mecR1和mec1基因表达。总之，此处报道的结果证明了松香酸对MRSP的抗菌活性，并支持将该化合物用作组合抗生素治疗中的潜在治疗剂。