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

• Published in: Antibiotics (Basel) 2020-05, Vol.9 (5), p.272
• Main Authors: Iseppi, Ramona, Di Cerbo, Alessandro, Aloisi, Piero, Manelli, Mattia, Pellesi, Veronica, Provenzano, Cinzia, Camellini, Stefania, Messi, Patrizia, Sabia, Carla
• Format: Article
• Language: English
• Subjects: Adhesion tests; Agar; Antibacterial activity; Antibiotic resistance; Antibiotics; Antimicrobial agents; Bacteria; Bacterial infections; biofilm; Biofilms; Carbapenemase; Diffusion; E coli; ESBL; Essential oils; Eucalyptus; Gram-negative bacteria; Klebsiella; Klebsiella pneumoniae; KPC; Low concentrations; MBL; Metabolites; Metallo-β-lactamase; Metallography; Microbiology; Microorganisms; Nosocomial infection; Nosocomial infections; Oils & fats; Pathogens; Polymerase chain reaction; Polystyrene; Polystyrene resins; Pseudomonas aeruginosa; Strains (organisms); β Lactamase
• ISSN: 2079-6382; 2079-6382
• DOI: 10.3390/antibiotics9050272

The aim of this study was to analyze the antibacterial activity of four essential oils (EOs), , , and in preventing the development and spread of extended-spectrum β-lactamase (ESBL)-producing and , metallo-beta-lactamase (MBL)-producing and carbapenemase (KPC)-producing . A total of 60 strains were obtained from the stock collection from the Microbiology Laboratory of Hesperia Hospital, Modena, Italy. Twenty ESBL-producing , 5 , 13 KPC-producing and 20 MBL-producing 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. and EOs showed the best antibacterial activity against all tested strains and, as revealed by agar disk diffusion assay, 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 and EOs, respectively. The EOs' antibacterial activity compared to antibiotics confirmed EO as the best antibacterial agent. 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 ( < 0.05 and < 0.01 for and EOs, respectively). A good antibacterial and anti-biofilm activity of and . 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.