Mazzantini Diletta, Massimino Mariacristina, Calvigioni Marco, Rossi Virginia, Celandroni Francesco, Lupetti Antonella, Batoni Giovanna, Ghelardi Emilia
Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa, Pisa, Italy.
Front Microbiol. 2024 Jul 3;15:1415400. doi: 10.3389/fmicb.2024.1415400. eCollection 2024.
Antibiotic resistance represents one of the most significant threats to public health in the 21st century. Polyphenols, natural molecules with antibacterial activity produced by plants, are being considered as alternative antimicrobial strategies to manage infections caused by drug-resistant bacteria. In this study, we investigated the antibacterial activity of a polyphenol mixture extracted from citrus fruits, against both antibiotic-susceptible and resistant strains of and .
Broth microdilution and time-kill curve experiments were used to test the extract anti-staphylococcal activity. Cytotoxicity was assessed by the hemolysis assay. The interaction between the mixture and antibiotics was investigated by the checkerboard assay. The effect of B alone and in combination with oxacillin on the membrane potential was investigated by the 3,3'-dipropylthiadicarbocyanine iodide assay. The ability of the extract to induce the development of resistance was verified by propagating for 10 transfers in the presence of sub-inhibitory concentrations.
The citrus extract was found to be active against all strains at remarkably low concentrations (0.0031 and 0.0063%), displaying rapid bactericidal effects without being toxic on erythrocytes. In particular, B was found to rapidly cause membrane depolarization. When combined with methicillin, meropenem, and oxacillin, the mixture displayed synergistic activity exclusively against methicillin-resistant strains. We additionally show that the sequential exposure of to sub-inhibitory concentrations did not induce the development of resistance against the extract.
Overall, these findings support the potential use of the citrus extract as promising option to manage staphylococcal infections and suggest that it may counteract the mechanism behind methicillin-resistance.
抗生素耐药性是21世纪对公共卫生最重大的威胁之一。多酚是植物产生的具有抗菌活性的天然分子，正被视为管理由耐药细菌引起的感染的替代抗菌策略。在本研究中，我们调查了从柑橘类水果中提取的多酚混合物对金黄色葡萄球菌的抗生素敏感菌株和耐药菌株的抗菌活性。
采用肉汤微量稀释法和时间-杀菌曲线实验来测试提取物的抗葡萄球菌活性。通过溶血试验评估细胞毒性。采用棋盘法研究混合物与抗生素之间的相互作用。通过3,3'-二丙基硫代二碳菁碘化物试验研究单独的B以及与苯唑西林联合使用对膜电位的影响。通过在亚抑制浓度下传代培养10次来验证提取物诱导耐药性产生的能力。
发现柑橘提取物在极低浓度（0.0031%和0.0063%）下对所有金黄色葡萄球菌菌株均有活性，显示出快速杀菌作用且对红细胞无毒。特别是，发现B能迅速引起膜去极化。当与甲氧西林、美罗培南和苯唑西林联合使用时，该混合物仅对耐甲氧西林菌株表现出协同活性。我们还表明，金黄色葡萄球菌在亚抑制浓度下的连续暴露不会诱导对该提取物产生耐药性。
总体而言，这些发现支持将柑橘提取物作为治疗葡萄球菌感染的有前景的选择，并表明它可能抵消耐甲氧西林背后的机制。
