Tackling Biofilm Resistance of Gram-Positive and Gram-Negative Bacteria Against Levofloxacin via Nanotechnology and Essential Oils

Introduction

The generation of biofilms by bacteria has become a major factor in the rise of antibiotic resistance. Lipid nano-capsules (LNCs) have recently emerged as an innovative platform for drug delivery, due to their unique properties and ability to carry a wide array of therapeutic chemical compounds.

Objectives

The objective of this research was to create, optimize, and evaluate the antibiofilm efficacy of a peppermint oil emulsion (o/w) containing levofloxacin against resistant bacteria via biofilm formation.

Methods

Essential oils, particularly peppermint oil known for its antifungal properties, were employed instead of traditional medium chain triglycerides to formulate lipid nanocarriers, utilizing alternating surfactant types (Solutol HS 15 and Cremophor EL) and differing oil to surfactant ratios (2:1 and 1:1). The LFX-LNCs formula, with a 2:1 oil to surfactant ratio, was selected for further investigation due to its physical properties, including particle size, zeta potential, transmission electron microscopy, and polydispersity index. The antibacterial efficiency of LFX-LNCs was evaluated, revealing their ability to eradicate established biofilms of Gram-negative pathogens, including Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa), as well as Gram-positive strains such as Staphylococcus aureus (S. aureus).

Results

The mean particle size of LFX-LNCs varied from 30.86 ± 0.54 nm to 68.36 ± 0.56 nm, demonstrating a narrow size distribution, a negative zeta potential (-1.56 ± 0.24 to -20.2 ± 2.15 mV), and a polydispersity index (PDI) ranging from 0.062 ± 0.006 to 0.26 ± 0.002. Lipid nanocapsules generally exhibit a spherical morphology within the nanometric size range when analyzed by transmission electron microscopy (TEM). The antimicrobial activity assessment revealed that EL 2:1 exhibited the most significant antimicrobial efficacy, characterized by a reduced particle size and an inhibition zone measuring up to (2.43 ± 0.24 cm), demonstrating promising results against several pathogenic strains, including P. aeruginosa, S. aureus, and E. coli.

Conclusion

This study illustrates the efficacy of LFX-LNCs in the treatment of non-healing wounds infected with biofilm-forming bacteria.

Graphical Abstract