Abstract
BACKGROUND: This study aims to evaluate the efficacy of baicalein, a flavonoid derived from Scutellaria baicalensis, against Staphylococcus aureus (S. aureus), focusing on its inhibitory and eradicative effects on biofilms, as well as its cellular cytotoxicity. The goal is to provide preliminary evidence for its potential application in the management of periprosthetic joint infection (PJI). METHODS: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of baicalein against the standard strain of S. aureus ATCC 29213, a clinical strain of methicillin-sensitive S. aureus 115 (MSSA 115), and a clinical strain of methicillin-resistant S. aureus 49 (MRSA 49) were determined using broth microdilution and colony counting methods. Bactericidal kinetics over a 24-h period were evaluated using a time-kill assay. Biofilm inhibition and eradication were assessed on 96-well and titanium alloy plates, while the cellular cytotoxicity of baicalein was examined using the cell counting kit-8 (CCK-8) assay on human primary synovial fibroblasts and chondrocytes. RESULTS: The MIC of baicalein was 32 μg/mL for the ATCC 29213, and 64 μg/mL for both MSSA115 and MRSA49. Meanwhile, the MBC for all three strains was 128 μg/mL. Baicalein exhibited a time-dependent bactericidal activity, with maximum efficacy at 24 h. Biofilm inhibition was evident at concentrations equal to or exceeding the MIC, as confirmed by biofilm biomass and metabolic activity assays, along with scanning electron and confocal laser microscope. However, baicalein was unable to completely eradicate preformed biofilms. Baicalein demonstrated significant cytotoxic effects on both synovial fibroblasts and chondrocytes after exposure for 16 and 24 h. CONCLUSIONS: Baicalein shows significant bactericidal effects and effectively inhibits S. aureus biofilm formation. These findings suggest its potential as a promising local antibacterial agent for postoperative continuous intra-articular lavage in the treatment of S. aureus-related early postoperative or acute hematogenous PJIs.