This study reported the volatile profile, the antimicrobial activity and the synergistic potential of essential oil (EO) from the Moroccan endemic Thymus atlanticus (Ball) Roussine, in combination with the antibiotics ciprofloxacin and fluconazole for the first time, to the best of our knowledge. The EO chemical composition was determined by gas chromatography coupled to mass spectrometry (GC-MS) analysis and the antimicrobial activity assessed by the disc diffusion method against three Gram positive (Bacillus subtilis, Micrococcus luteus, Staphylococcus aureus) and three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli and one clinical isolate, Klebsiella pneumonia). The antifungal activity was evaluated in four pathogenic yeasts (Candida albicans, C. glabrata, C. krusei and C. parapsilosis). The minimum inhibition concentration (MIC) and the synergistic effect with ciprofloxacin and fluconazole were determined by the two-fold dilution technique and checkerboard test, respectively. Twenty-one constituents were identified by GC-MS in the EO, including carvacrol (21.62%) and borneol (21.13%) as the major components. The EO exhibited a significant antimicrobial activity with inhibition zones ranging from 0.7 mm to 22 mm for P. aeruginosa and B. subtilis, respectively, and MIC values varying from 0.56 mg/mL to 4.47 mg/mL. The fractional inhibitory concentration index (FICI) values ranged from 0.25 to 0.50 for bacteria and from 0.25 to 0.28 for yeasts. The maximum synergistic effect was observed for K. pneumonia with a 256-fold gain of antibiotic MIC. Our results have suggested that EO from T. atlanticus may be used alone or in association with antibiotics as a new potential alternative to prevent and control the emergence of resistant microbial strains both in the medical field and in the food industry.

中文翻译：

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摩洛哥地方性胸腺大西洋（球）香芹精油与常规抗生素组合的化学成分、抗菌和协同作用的新见解

据我们所知，这项研究首次报告了摩洛哥地方性胸腺(球) Roussine精油 (EO)与抗生素环丙沙星和氟康唑的挥发性特征、抗菌活性和协同潜力. EO 化学成分通过气相色谱-质谱联用 (GC-MS) 分析确定，并通过圆盘扩散法评估对三种革兰氏阳性菌（枯草芽孢杆菌、藤黄微球菌、金黄色葡萄球菌）和三种革兰氏阴性菌的抗菌活性（铜绿假单胞菌、大肠杆菌和一种临床分离株，肺炎克雷伯菌）。在四种致病酵母（白色念珠菌、光滑念珠菌、克柔念珠菌和近平滑念珠菌）中评估了抗真菌活性。最小抑制浓度（MIC）和与环丙沙星和氟康唑的协同作用分别通过两倍稀释技术和棋盘试验确定。EO 中 GC-MS 鉴定出 21 种成分，其中香芹酚 (21.62%) 和冰片 (21.13%) 为主要成分。EO 表现出显着的抗菌活性，对铜绿假单胞菌和枯草芽孢杆菌的抑菌圈范围为 0.7 毫米至 22 毫米和 MIC 值从 0.56 毫克/毫升到 4.47 毫克/毫升不等。细菌的分数抑制浓度指数 (FICI) 值范围为 0.25 至 0.50，酵母的范围为 0.25 至 0.28。对肺炎克雷伯菌观察到最大的协同作用，抗生素 MIC 增加了 256 倍。我们的研究结果表明，来自大西洋的EO可以单独使用或与抗生素联合使用，作为预防和控制医疗领域和食品工业中耐药微生物菌株出现的新潜在替代品。