Microbiological evaluation of an experimental denture cleanser containing essential oil of <i>Lippia sidoides</i>

The antimicrobial activity of an experimental solution containing essential oil of <i>Lippia sidoides</i> for denture cleaning was evaluated by (1) minimum inhibitory (MIC) and fungicidal/bactericidal concentration (MFC/MBC) tests against <i>Candida albicans</i>, <i>Staphylococcus aureus</i>, and <i>Pseudomona aeruginosa</i>; (2) the metabolic activity of <i>C. albicans</i> biofilm formed on flat-bottom microplates and denture base specimens based on the reduction of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT); and (3) scanning electron microscopy, to evaluate the fungal biofilm morphology. The solution showed antimicrobial action against the pathogens tested (<i>C. albicans</i> - MIC and MFC: 19.53 µg ml⁻¹, <i>S. aureus</i> - MIC and MBC: 78.12 µg ml⁻¹, <i>P. aeruginosa</i> - MIC: 625 µg ml⁻¹, MBC: 2,500 µg ml⁻¹), reduced the metabolic activity of <i>C. albicans</i> biofilm up to 97%, and caused cell wall damage at low concentrations (195.3–390.6 µg ml⁻¹) and in short time periods (20 min). Therefore, the experimental solution has the potential to be used as an alternative in the prevention and treatment of denture-induced infections.