The aim of this study was to analyze the antibacterial activity of four essential oils (EOs), Melaleuca alternifolia, Eucalyptus globulus, Mentha piperita, and Thymus vulgaris, in preventing the development and spread of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae, metallo-beta-lactamase (MBL)-producing Pseudomonas aeruginosa and carbapenemase (KPC)-producing Klebsiella pneumoniae. A total of 60 strains were obtained from the stock collection from the Microbiology Laboratory of Hesperia Hospital, Modena, Italy. Twenty ESBL-producing E. coli, 5 K. pneumoniae, 13 KPC-producing K. pneumoniae, and 20 MBL-producing P. aeruginosa were cultured and reconfirmed as ESBL and carbapenamase producers. Polymerase chain reaction was used for the detection of genes responsible for antibiotic resistance (ESBL and KPC/MBL). Antibacterial activity of the EOs was determined using the agar disk diffusion assay, and minimal inhibitory concentrations (MICs) were also evaluated. Lastly, adhesion capability and biofilm formation on polystyrene and glass surfaces were studied in 24 randomly selected strains. M. alternifolia and T. vulgaris EOs showed the best antibacterial activity against all tested strains and, as revealed by agar disk diffusion assay, M. alternifolia was the most effective, even at low concentrations. This effect was also confirmed by MICs, with values ranging from 0.5 to 16 µg/mL and from 1 to 16 µg/mL, for M. alternifolia and T. vulgaris EOs, respectively. The EOs’ antibacterial activity compared to antibiotics confirmed M. alternifolia EO as the best antibacterial agent. T. vulgaris EO also showed a good antibacterial activity with MICs lower than both reference antibiotics. Lastly, a significant anti-biofilm activity was observed for the two EOs (*P < 0.05 and **P < 0.01 for M. alternifolia and T. vulgaris EOs, respectively). A good antibacterial and anti-biofilm activity of M. alternifolia and T. vulgaris EOs against all selected strains was observed, thus demonstrating a future possible use of these EOs to treat infections caused by ESBL/carbapenemase-producing strains, even in association with antibiotics.

中文翻译：

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精油对人类医院感染涉及的广谱β-内酰胺酶（ESBL）/产生碳青霉烯酶的革兰氏阴性细菌浮游生物和生物膜细胞的体外活性。

这项研究的目的是分析四种精油（EOs），互叶白千层，桉木，薄荷（Mentha piperita）和百里香（Thymus vulgaris）在预防产生和扩散广谱β-内酰胺酶（ESBL）产生中的抗菌活性。大肠杆菌和肺炎克雷伯菌，产金属β-内酰胺酶（MBL）的铜绿假单胞菌和碳青霉烯酶（KPC）产生的肺炎克雷伯菌。从意大利摩德纳Hesperia医院微生物实验室的菌种库中获得了总共60株。产生ESBL的二十种大肠杆菌，5肺炎克雷伯菌，13产KPC肺炎克雷伯菌，和20 MBL生产铜绿假单胞菌中培养并再次确认作为ESBL和carbapenamase生产者。聚合酶链反应用于检测引起抗生素抗性的基因（ESBL和KPC / MBL）。使用琼脂圆盘扩散测定法确定EO的抗菌活性，并评估最小抑菌浓度（MIC）。最后，在24种随机选择的菌株中研究了在聚苯乙烯和玻璃表面上的粘附能力和生物膜形成。互生念珠菌和寻常型念珠菌EOs对所有测试菌株均表现出最佳的抗菌活性，正如琼脂圆盘扩散试验所揭示的那样，互生念珠菌即使在低浓度下也是最有效的。MIC也证实了这种效应，互生分枝杆菌和寻常型EO的EO值分别为0.5至16 µg / mL和1至16 µg / mL 。与抗生素相比，EOs的抗菌活性证实了互叶孢霉EO是最好的抗菌剂。寻常T. EO也显示出良好的抗菌活性，MIC均低于两种参考抗生素。最后，两个EOs观察到了显着的抗生物膜活性（互生念珠菌和寻常型念珠菌的* P <0.05和** P <0.01EO）。有良好的抗菌和抗生物膜活性M. alternifolia和Ť。观察到针对所有选定菌株的寻常的EOs，因此证明了这些EOs将来有可能用于治疗由ESBL /卡培南生产酶的菌株引起的感染，甚至与抗生素结合使用。