Biofilm destruction activity of α-tocopherol against Staphylococcus aureus, Proteus mirabilis, and Pseudomonas aeruginosa

Abstract

Antibiotic resistance and the persistence of sessile cells within biofilms complicate the eradication of biofilm-related infections using conventional antibiotics. This highlights the necessity for alternate therapy methods. The objective of this study was to investigate the biofilm destruction activity of α-tocopherol against Staphylococcus aureus, Proteus mirabilis, and Pseudomonas aeruginosa on polystyrene. α-Tocopherol showed significant biofilm destruction activity on the pre-formed biofilms of S. aureus (45%-46%), Pr. mirabilis (42%-54%), and Ps. aeruginosa (28%). Resazurin assay showed that α-tocopherol disrupted all bacterial biofilms without interfering with their cell viability. Scanning electron microscope images showed lower bacterial cell count and less compacted cell aggregates on polystyrene surfaces after treatment with α-tocopherol. This study demonstrated the biofilm destruction activity of α-tocopherol against S. aureus, Pr. mirabilis, and Ps. aeruginosa. α-Tocopherol could potentially be used to decrease biofilm-associated infections of these bacteria.

Keywords: Gram-negative bacteria; Gram-positive bacteria; anti-biofilm; antimicrobial; biofilm inhibition; vitamin E.

Figure 1.

Biofilm destruction after treatment with α-tocopherol at various concentrations against (A) S. aureus ATCC 6538P, (B) Ps. aeruginosa ATCC 27853, and (C) Pr. mirabilis ATCC 12453. The NC was bacteria suspension in BHI broth with 0.5% DMSO water, while the PC was bacteria suspension in BHI broth with 1% sodium hypochlorite. All experiments were carried out in triplicates, and results were expressed as mean percentage biofilm destruction ± standard deviation. ^abcDifferent letters indicate significant differences in biofilm destruction at ***P < .001 or *P < .05.

Figure 2.

Cell viability within bacterial biofilms after treatment with α-tocopherol at various concentrations against (A) S. aureus ATCC 6538P, (B) Ps. aeruginosa ATCC 27853, and (C) Pr. mirabilis ATCC 12453. The NC was bacteria suspension in BHI broth with 0.5% DMSO, while the PC was bacteria suspension in BHI broth with 1% sodium hypochlorite. All experiments were carried out in triplicates, and results were expressed as mean percentage cell viability ± standard deviation. ^abDifferent letters indicate significant differences in cell viability at P < .001.

Figure 3.

Effect of α-tocopherol on the bacterial cell density and distribution of biofilm after treatment with α-tocopherol at MBDC for (A) S. aureus ATCC 6538P, (B) Ps. aeruginosa ATCC 27853, and (C) Pr. mirabilis ATCC 12453. Images were taken under 2500× magnification at 10 kV. The NC was bacteria suspension in BHI broth with 0.5% DMSO. The PC was bacteria suspension in BHI broth with 1% sodium hypochlorite. The MDBC was 0.01 mg ml⁻¹ for S. aureus ATCC 6538P and Pr. mirabilis ATCC 12453, and 2 mg ml⁻¹ for Ps. aeruginosa ATCC 27853.