Antimicrobial and anti-biofilm activity of Hypericum brasiliense extract and its fractions on Staphylococcus of canine origin

The growing resistance to antimicrobials, partly due to the ability to form biofilms, poses a challenge for developing new antimicrobial agents. This study assessed the antimicrobial and antibiofilm activity of Hypericum brasiliense extract, Japonicin, and Uliginosin-B against clinical isolates of S. pseudintermedius and S. coagulans from dogs. The minimal inhibitory concentration (MIC) and the minimal bactericidal concentration (MBC) were determined. In vitro antibiofilm activity was evaluated and showed promising results in young (6 h) and mature (24 h) biofilms. S. pseudintermedius and S. coagulans were highly sensitive to all tested substances. All tested isolates exhibited low MIC and MBC values, particularly for Uliginosin-B. Japonicin demonstrated higher MIC and MBC values. The analysis of antibiofilm activity revealed inhibition of biofilm formation and even disruption of pre-formed biofilms at various concentrations, including sub-inhibitory ones. H. brasiliense and its fractions exhibited antimicrobial and antibiofilm activity, offering promising prospects for treating infections caused by biofilm-forming bacteria.