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Antibacterial Potential of Essential Oils and Silver Nanoparticles against Multidrug-Resistant Staphylococcus
Gabriele Meroni1, Giulia Laterza1,2, Alexios Tsikopoulos3
1One Health Unit, Department of Biomedical, Surgical and Dental Sciences, School of Medicine, University of Milan, Via Pascal 36, 20133 Milan, Italy.
Abstract:
Staphylococcus pseudintermedius is an emergent zoonotic agent associated with multidrug resistance (MDR). This work aimed to describe the antibacterial activity of four essential oils (EOs) and silver nanoparticles (AgNPs) against 15 S. pseudintermedius strains isolated from pyoderma. The four EOs, namely Rosmarinus officinalis (RO), Juniperus communis (GI), Citrus sinensis (AR), and Abies alba (AB), and AgNPs were used alone and in combination to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). All strains were MDR and methicillin-resistant. Among the antibiotic cohort, only rifampicin, doxycycline, and amikacin were effective. EOs' chemical analysis revealed 124 compounds belonging to various chemical classes. Of them, 35 were found in AR, 75 in AB, 77 in GI, and 57 in RO. The monoterpenic fraction prevailed over the sesquiterpenic in all EOs. When EOs were tested alone, AB showed the lowest MIC followed by GI, AR, and RO (with values ranging from 1:128 to 1:2048). MBC increased in the following order: AB, AR, GI, and RO (with values ranging from 1:512 to 1:2048). MIC and MBC values for AgNPs were 10.74 mg/L ± 4.23 and 261.05 mg/L ± 172.74. In conclusion, EOs and AgNPs could limit the use of antibiotics or improve the efficacy of conventional therapies.
Insights
Essential oils and silver nanoparticles show antibacterial activity against multidrug-resistant Staphylococcus pseudintermedius. These natural compounds may reduce antibiotic use and enhance current treatments for resistant bacterial infections.
Area of Science:
- Microbiology
- Nanotechnology
- Natural Products Chemistry
Background:
- Staphylococcus pseudintermedius is an emerging zoonotic pathogen known for multidrug resistance (MDR).
- MDR S. pseudintermedius strains, particularly methicillin-resistant ones, pose a significant challenge in treating pyoderma.
- Limited effective antibiotic options exist for MDR S. pseudintermedius infections.
Purpose of the Study:
- To evaluate the antibacterial efficacy of four essential oils (EOs) and silver nanoparticles (AgNPs) against MDR S. pseudintermedius.
- To determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of EOs and AgNPs, individually and in combination.
- To analyze the chemical composition of the EOs and correlate it with their observed antibacterial activity.
Main Methods:
- Antibacterial activity testing (MIC and MBC) of four EOs (Rosmarinus officinalis, Juniperus communis, Citrus sinensis, Abies alba) and AgNPs against 15 S. pseudintermedius strains.
- Gas chromatography-mass spectrometry (GC-MS) for EO chemical composition analysis.
- Determination of antibiotic susceptibility profiles for all bacterial isolates.
Main Results:
- All 15 S. pseudintermedius strains were multidrug-resistant and methicillin-resistant.
- Abies alba EO exhibited the lowest MIC values (1:128 to 1:2048), followed by Juniperus communis, Citrus sinensis, and Rosmarinus officinalis.
- AgNPs showed MIC and MBC values of 10.74 mg/L ± 4.23 and 261.05 mg/L ± 172.74, respectively. The monoterpenic fraction was dominant in all EOs.
Conclusions:
- Essential oils and silver nanoparticles demonstrate significant antibacterial potential against MDR S. pseudintermedius.
- These natural agents could serve as alternatives or adjuncts to conventional antibiotics.
- Further research into EOs and AgNPs may lead to novel therapeutic strategies for resistant bacterial infections.
