Lugol's solution eradicates Staphylococcus aureus biofilm in vitro

Area of Science:

• Microbiology
• Antimicrobial Research
• Biofilm Studies

Background:

• Staphylococcus aureus biofilms pose a significant challenge in treating infections due to their inherent resistance.
• Conventional antibiotics may be less effective against bacteria residing within biofilms.
• Exploring alternative antimicrobial agents is crucial for combating biofilm-related infections.

Purpose of the Study:

• To evaluate the in vitro antibacterial efficacy of Lugol's solution, acetic acid, and boric acid against Staphylococcus aureus biofilms.
• To compare the effectiveness of these agents in both planktonic and biofilm states.

Main Methods:

• Tested Lugol's solution (1%, 0.1%, 0.05%), acetic acid (5%), and boric acid (4.7%) against 30 clinical strains of Staphylococcus aureus.
• Assessed planktonic susceptibility using disk diffusion.
• Evaluated antiseptic effects on biofilms using metabolic activity assays (Biofilm-oriented antiseptic test - BOAT), bacterial culturing, and confocal laser scanning microscopy with LIVE/DEAD staining.

Main Results:

• Lugol's solution and acetic acid were effective against planktonic S. aureus; boric acid showed slightly reduced efficacy.
• In biofilms, Lugol's solution significantly reduced metabolic activity and demonstrated potent bactericidal effects.
• Acetic acid showed some reduction in metabolic activity but limited bactericidal effect, while boric acid had no significant impact on biofilm metabolic activity or bacterial viability.

Conclusions:

• Lugol's solution (1.0% and 0.1%) effectively eradicated Staphylococcus aureus in biofilm.
• Lugol's solution presents a viable alternative to conventional topical antibiotics for suspected S. aureus biofilm infections.
• Potential applications include external otitis, pharyngitis, and wound infections.