Ouzakar Sanaa, Senhaji Nadia Skali, Harsal Abdeltif El, Abrini Jamal
Biotechnology and Applied Microbiology Team, Research Laboratory of Applied Chemistry and Microbiology and Biotechnology, Department of Biology, Faculty of Sciences, Abdelmalek Essaadi University, Tetouan, Morocco.
Int Microbiol. 2025 Apr;28(4):691-701. doi: 10.1007/s10123-024-00576-w. Epub 2024 Aug 12.
The massive emergence of antimicrobial resistance in recent decades has rendered the use of a single-agent strategy ineffective. Consequently, the combination of different therapeutic agents has emerged as a promising new approach. The aim of the present study was to investigate the combined effect of Chlorella vulgaris methanol extract (CVME) and Origanum elongatum essential oil (OEEO) on methicillin-resistant Staphylococcus aureus (MRSA). Thus, the antibacterial activity of OEEO and CVME on Escherichia coli, Staphylococcus aureus, and MRSA was evaluated using the agar well diffusion and broth microdilution methods. The killing activity of CVME and OEEO, individually and in combination, on MRSA ATCC 43300 was tested using the time-kill assay. The synergistic effect was examined by determining the fractional inhibitory concentration index (FICI) using the checkerboard test. The results showed very significant antibacterial activity against all the bacteria tested, for both OEEO and CVME, with minimum inhibitory concentrations (MICs) ranging from 0.125 to 0.25% (v/v) for OEEO and from 3.12 to 6.25 mg mL for CVME. Minimum bactericidal concentration (MBC) values for OEEO and CVME were in the range 0.125-0.5% (v/v) and 6.25-12.5 mg mL, respectively. The inhibition zones associated with OEEO were distinctly greater than those associated with CVME for all the bacteria examined. When used individually, the time-kill curves of OEEO and CVME revealed a dose-dependent effect on MRSA proliferation. Compared with controls, both agents were able to prolong the latent phase of growth curves and decelerate bacterial growth. The killing effect of OEEO on MRSA was considerably higher than that observed with CVME. OEEO prevented MRSA proliferation at only 1/2 of its MIC, while the CVME did so at 2 times its MIC. The combination of OEEO with CVME demonstrated a synergistic effect against MRSA, with a FIC index value of 0.49. The findings therefore suggest that the combination of C. vulgaris methanol extract and O. elongatum essential oil at very low doses may be promising anti-MRSA candidates. A search of the published literature revealed that, to our knowledge, no studies have yet been carried out on the antibacterial potential of combining essential oils and microalgae extracts in the fight against MRSA.
近几十年来，抗菌药物耐药性的大量出现使得单药治疗策略失效。因此，不同治疗药物的联合使用已成为一种有前景的新方法。本研究的目的是调查小球藻甲醇提取物（CVME）和长叶牛至精油（OEEO）对耐甲氧西林金黄色葡萄球菌（MRSA）的联合作用。因此，采用琼脂孔扩散法和肉汤微量稀释法评估了OEEO和CVME对大肠杆菌、金黄色葡萄球菌和MRSA的抗菌活性。使用时间杀菌试验测试了CVME和OEEO单独及联合使用对MRSA ATCC 43300的杀菌活性。通过棋盘法测定分数抑菌浓度指数（FICI）来检测协同效应。结果显示，OEEO和CVME对所有测试细菌均具有非常显著的抗菌活性，OEEO的最低抑菌浓度（MIC）范围为0.125%至0.25%（v/v），CVME的最低抑菌浓度范围为3.12至6.25 mg/mL。OEEO和CVME的最低杀菌浓度（MBC）值分别在0.125% - 0.5%（v/v）和6.25 - 12.5 mg/mL范围内。对于所有检测的细菌，与OEEO相关的抑菌圈明显大于与CVME相关的抑菌圈。单独使用时，OEEO和CVME的时间杀菌曲线显示出对MRSA增殖的剂量依赖性效应。与对照组相比，两种药物都能够延长生长曲线的潜伏期并减缓细菌生长。OEEO对MRSA的杀菌效果明显高于CVME。OEEO仅在其MIC的1/2时就能阻止MRSA增殖，而CVME则需要在其MIC的2倍时才能做到。OEEO与CVME的组合对MRSA表现出协同效应，FIC指数值为0.49。因此，研究结果表明，极低剂量的小球藻甲醇提取物和长叶牛至精油组合可能是有前景的抗MRSA候选药物。对已发表文献的检索表明，据我们所知，尚未有关于精油和微藻提取物联合对抗MRSA抗菌潜力的研究。
