Objective: Boric acid (BA), a weak acid of boron, is used in many areas and one of the most important boron reserves is located in Türkiye. This study, in addition to investigating how biofilm formation is affected by BA in a dose-dependent manner, aimed to evaluate the minimum inhibitory concentrations (MICs), minimum fungicidal concentrations (MFCs), minimum bactericidal concentration (MBCs) and, anti-biofilm activity of BA against the medically important bacteria and yeast species.
Materials and Methods: In total 19 medically important bacteria and yeast reference strains are chosen where the MICs, MFCs and MBCs values are calculated with broth microdilution method as indicated in Clinical and Laboratory Standards Institute (CLSI) criteria. In addition to the viable microorganisms in biofilm being enumerated, the rates of biofilm inhibition are evaluated with the modified Crystal violet staining method.
Results: MICs values for the bacteria ranged between 61.83–1.93 mg/ml. The lowest MIC value (0.97 mg/ml) and the high rates of biofilm inhibition (93.39%) of fungi strain belong to C. albicans ATCC 10231. In addition, it was observed that all dilutions of BA provided significant reductions in viable microorganisms in the biofilm structure.
Conclusion: Antimicrobial and anti-biofilm activity of BA against bacterial and fungal strains with medical importance may indicate that BA may be a promising alternative against medically important pathogens.