肉桂（Cinnamomum verum J. Presl）、苦橙叶（Citrus x aurantium L.）、玫瑰天竺葵（Pelargonium graveolens L'Hér）和百里香（Thymus vulgaris L.）精油软膏对犬外耳炎铜绿假单胞菌分离株的体外抗菌潜力

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中文摘要

背景/目的： 外耳炎是犬常见感染。最重要的病原体是铜绿假单胞菌，且由于该病原体的抗生素耐药性，越来越多的病例难以治疗。方法：我们使用气相色谱-质谱联用（GC-MS）测定了肉桂（Cinnamomum verum J. Presl）、苦橙叶（Citrus x aurantium L.）、玫瑰天竺葵（Pelargonium graveolens L'Hér）和百里香（Thymus vulgaris L.）精油的组成。随后采用生物自显影法鉴定抗菌成分。将2.5%和5%浓度的精油加入四种不同软膏基质（如甲基纤维素水凝胶、油性软膏、硬脂酸软膏和胆固醇凡士林）中，并使用含抗生素产品Marbogen复合物作为对照，在六株铜绿假单胞菌分离株的菌苔上测试体外抗菌效果。在4°C和27°C下对甲基纤维素基软膏的保存性监测12个月，每月评估效力损失。结果：甲基纤维素水凝胶（HM）在支持每种精油的治疗效力方面最为有效，对于5%肉桂、苦橙叶、玫瑰天竺葵和百里香，分别使暴露区域的细菌计数减少99.999%、100%、100%和100%。基于精油的HM软膏在15分钟内起效，30、45和60分钟后仅有轻微改善。肉桂在HM基质中应用时最为有效。与HM和US凝胶基质相比，油性软膏和胆固醇凡士林的抗菌支持作用显著较低。水凝胶制剂中精油的抗菌效力因精油种类（p < 0.001）、其浓度（p < 0.001）、暴露时间（p < 0.001）和所用铜绿假单胞菌分离株（p < 0.001）而显著不同。肉桂油表现出最高效力，在15分钟内对所有分离株实现近乎完全的细菌清除。2.5%和5%浓度之间无显著差异（EMM：0.016 vs. 0.004；p = 0.904）。结论：我们的结果表明，当与有效的凝胶基质联合使用时，基于精油的产品可以成为抗生素的有效替代品。

英文摘要

Background/Objectives: Otitis externa is a common infection in dogs. The most important aetiological agent is Pseudomonas aeruginosa, and an increasing number of cases are proving difficult to treat due to this pathogen's antibiotic resistance. Methods: We determined the composition of cinnamon (Cinnamomum verum J. Presl), petitgrain (Citrus x aurantium L.), rose geranium (Pelargonium graveolens L'Hér), and thyme (Thymus vulgaris L.) essential oils (EOs) using gas chromatography-mass spectrometry (GC-MS). We then used the bioautographic method to identify antibacterial components. Two-and-a-half- and five percent concentrations of the essential oils were added to four different ointment bases, such as hydrogelum methylcellulose, unguentum oleosum, unguentum stearini, and vaselinum cholesterinatum, and the in vitro antibacterial effects were tested on lawns of six P. aeruginosa isolates using the antibiotic-containing product Marbogen complex as a control. The keepability of the methylcellulose-based ointments was monitored at 4 °C and 27 °C for 12 months, with efficacy losses evaluated monthly. Results: Hydrogel methylcellulose (HM) was the most effective at supporting the therapeutic efficacy of each oil, reducing the bacterial count on the exposed area by 99.999%, 100%, 100%, and 100% in the case of 5% cinnamon, petitgrain, rose geranium, and thyme, respectively. EO-based HM ointments take effect within 15 min, with only slight improvement after 30, 45, and 60 min. Cinnamon was the most effective when applied in the HM matrix. In contrast to the HM and US gel matrices, the antibacterial supportive effects of Unguentum oleosum and Vazelinum cholestrinatum were drastically lower. The antimicrobial efficacy of essential oils in hydrogel formulation varied significantly depending on the type of oil (p < 0.001), its concentration (p < 0.001), the exposure time (p < 0.001), and the P. aeruginosa isolate used (p < 0.001). Cinnamon oil demonstrated the highest efficacy, achieving near-complete bacterial elimination across all isolates within 15 min. There was no significant difference between the 2.5% and 5% concentrations (EMM: 0.016 vs. 0.004; p = 0.904). Conclusions: Our results demonstrate that essential oil-based products can be effective alternatives to antibiotics when used in conjunction with an effective gel matrix.