Geopropolis and anacardic acid: bactericidal and antibiofilm action on multidrug-resistant Staphylococcus epidermidis and modulatory effects on dexamethasone-suppressed macrophages in vitro

OBJECTIVES: Staphylococcus epidermidis is a public health concern due to its antimicrobial resistance, causing infections that can worsen in immunosuppressed patients. Geopropolis (GEO) is produced by Meliponines and contains anacardic acid (AA). This study evaluated the antibacterial action of GEO and AA, and their modulatory effects on macrophages, both with and without dexamethasone (DEX) treatment. METHODS: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of GEO, AA, ceftaroline (CPT), and gentamicin (GEN) were evaluated. The effect of the treatments was evaluated on the bacteria's ability to produce biofilm and on THP-1 cells differentiated into macrophages with or without DEX, evaluating cell viability, TLR-2 expression, eicosanoids (PGE2 and LTB4), cytokine (TNF-α, IL-1β, IL-6, and IL-10), and the bactericidal activity against S. epidermidis. KEY FINDINGS: GEO exhibited no antibacterial activity. AA had a more efficient MIC and MBC than the antimicrobials and inhibited biofilm formation. AA did not affect TLR-2 expression. It increased the bactericidal capacity of macrophages suppressed or not by DEX, and inhibited IL-10 production. Our findings suggest AA practical applications, as antibacterial coatings, wound care formulations, and infection control. CONCLUSIONS: AA has antibacterial and immunomodulatory properties and could be an effective adjuvant in treating S. epidermidis infection.