Combined Antimicrobial Effects of <i>Lactiplantibacillus plantarum</i>-Derived Biosurfactant and Supercritical CO₂-Extracted <i>Rosmarinus officinalis</i> Against Multidrug-Resistant <i>Staphylococcus aureus</i>

The global prevalence of antibiotic-resistant bacteria, such as <i>Staphylococcus aureus</i>, presents a substantial challenge to public health, necessitating the development of innovative therapeutic strategies to combat these infections. This study examined the synergistic effects of a biosurfactant (BS) derived from <i>Lactiplantibacillus plantarum</i> and a novel extract from <i>Rosmarinus officinalis</i> (RoME) obtained through supercritical CO₂ extraction against <i>S. aureus</i> sourced from the microbiology laboratory at King Salman Hospital in Ha’il, Saudi Arabia. Antibacterial efficacy was determined using minimum inhibitory concentration (MIC) assays, assessments of bacterial membrane damage, and qRT-PCR analysis of genes associated with antibiotic resistance. The findings revealed that the <i>S. aureus</i> strain exhibited resistance to multiple antibiotics with a resistance score of 0.44. RoME and BS demonstrated MICs of 0.125 mg/mL and 0.5 mg/mL, respectively. The assays indicated significant bacterial membrane damage and reduced expression of the <i>norA</i>, <i>mdeA</i>, and <i>sel</i> genes, which are implicated in resistance and virulence, respectively. The combination of BSs with plant extracts may provide innovative approaches for treating infections caused by multidrug-resistant bacteria, highlighting the potential of probiotic-derived BSs in combination with plant extracts.