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

Abstract

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.

Plants with Antimicrobial Activity Growing in Italy: A Pathogen-Driven Systematic Review for Green Veterinary Pharmacology Applications

“…[102]; Calycotome villosa [78]; Juniperus spp. [79]; Allium ampeloprasum [54]; Allium sativum [24]; Melaleuca alternifolia [113];…”

Dietary Supplementation of Nile Tilapia (Oreochromis niloticus) With Panax ginseng Essential Oil: Positive Impact on Animal Health and Productive Performance, and Mitigating Effects on Atrazine- Induced Toxicity

“…EOs contain a high amount of functional bioactive phytochemicals, which offer some unique health benefits for fishes and shrimps farming (Chakraborty and Hancz, 2011;Chakraborty et al, 2014;Ahmadifar et al, 2021). Indeed, EOs have been shown to exert several important activities, including antimicrobial and antiparasitic (Iseppi et al, 2020;Dawood et al, 2021), immunostimulating (Dawood et al, 2020) anti-stress (Souza et al, 2019), and growth promoting (Magouz et al, 2021). Consistently, several studies provided evidence supporting the dietary use of EOs in aquaculture as possible alternative strategies for improving disease resistance, antioxidant capacity, growth performance, and the overall welfare of farmed fishes.…”

Current Antibiotic Resistance Trends of Uropathogens in Central Europe: Survey from a Tertiary Hospital Urology Department 2011–2019

“…Antimicrobial agents with non-traditional therapeutic targets (virulence factors inactivators, inhibitors of adhesion and biofilm formation, monoclonal antibodies against bacterial exotoxins, quorum-sensing and other communication channels disrupting agents or those countering immune evasion) are being developed but not yet ready for clinical use [ 28 ]. The same holds true for alternative substances with antimicrobial effect, such as zinc-oxide nano-particles [ 29 ], cell-free probiotic suspensions [ 30 ], essential oils [ 31 ], or phage therapy [ 32 ].…”