In Vitro Activity of Essential Oils Against Planktonic and Biofilm Cells of Extended-Spectrum β-Lactamase (ESBL)/Carbapenamase-Producing Gram-Negative Bacteria Involved in Human Nosocomial Infections

• Main Authors: Ramona Iseppi (Author), Alessandro Di Cerbo (Author), Piero Aloisi (Author), Mattia Manelli (Author), Veronica Pellesi (Author), Cinzia Provenzano (Author), Stefania Camellini (Author), Patrizia Messi (Author), Carla Sabia (Author)
• Format: Book
• Published: MDPI AG, 2020-05-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.

Summary

The aim of this study was to analyze the antibacterial activity of four essential oils (EOs), <i>Melaleuca alternifolia</i>, <i>Eucalyptus globulus</i>, <i>Mentha piperita,</i> and <i>Thymus vulgaris,</i> in preventing the development and spread of extended-spectrum β-lactamase (ESBL)-producing <i>Escherichia coli</i> and <i>Klebsiella pneumoniae</i>, metallo-beta-lactamase (MBL)-producing <i>Pseudomonas aeruginosa</i> and carbapenemase (KPC)-producing <i>Klebsiella pneumoniae</i>. A total of 60 strains were obtained from the stock collection from the Microbiology Laboratory of Hesperia Hospital, Modena, Italy. Twenty ESBL-producing <i>E. coli</i>, 5 <i>K. pneumoniae</i>, 13 KPC-producing <i>K. pneumoniae,</i> and 20 MBL-producing <i>P. aeruginosa</i> 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. <i>M. alternifolia</i> and <i>T. vulgaris</i> EOs showed the best antibacterial activity against all tested strains and, as revealed by agar disk diffusion assay, <i>M. alternifolia</i> 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 <i>M. alternifolia</i> and <i>T. vulgaris</i> EOs, respectively. The EOs' antibacterial activity compared to antibiotics confirmed <i>M. alternifolia</i> EO as the best antibacterial agent. <i>T. vulgaris</i> 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 (<i>*P</i> < 0.05 and <i>**P</i> < 0.01 for <i>M. alternifolia</i> and <i>T. vulgaris</i> EOs, respectively). A good antibacterial and anti-biofilm activity of <i>M. alternifolia</i> and <i>T</i>. <i>vulgari</i>s 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.

Item Description

10.3390/antibiotics9050272
2079-6382