Abstract
Background:
Antimicrobial resistance (AMR), particularly methicillin-resistant Staphylococcus aureus (MRSA), has posed a significant challenge to global health care. The increasing ineffectiveness of conventional antibiotics has driven the need for alternative antimicrobial agents. Rosmarinus officinalis L. (rosemary) is known for its diverse biological properties, including antibacterial and anti-biofilm activities.

Aim:
This study aimed to investigate and compare the antibacterial and anti-biofilm effects of different R. officinalis L. solvent extracts against MRSA.

Methods:
Antibacterial efficacy was determined using the well-diffusion method, followed by the assessment of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against 10 MRSA strains. The antibiofilm potential was analyzed using a crystal violet assay. In addition, cytotoxicity was evaluated using an MTT assay on HCT-116 colorectal carcinoma cells.

Results:
Methanol demonstrated the highest antibacterial activity among the tested extracts. The MIC values ranged between 0.108 and 0.320 mg/ml, with corresponding MBC results confirming strong bactericidal effects. The antibiofilm analysis indicated that the ethyl acetate extract exhibited the greatest inhibition of MRSA biofilm formation, followed by the dichloromethane and methanol extracts.

Conclusion:
Rosmarinus officinalis L. (rosemary) extracts, particularly those extracted with methanol and ethyl acetate, exhibited strong antibacterial and anti-biofilm effects against MRSA.

Key words: Antibiofilm; Antibacterial; MRSA; Antibiotic resistance; Rosemary.