Antibacterial and Antibiofilm Activity of Hypericum Perforatum L. Extract on Bacteria Isolated from Used Cosmetic Tools

Cosmetic products and shared cosmetic tools can serve as reservoirs for pathogenic microbes, increasing the risk of cross-contamination and infection. This study evaluated the antibacterial and antibiofilm activities of Hypericum perforatum L. extracts against bacteria isolated from cosmetic tools used in beauty salons in Istanbul, Turkey. A total of 40 tools were examined, and bacterial identification was performed using selective media. Antibiotic resistance profiles were determined using the Kirby–Bauer disk diffusion method, and the multiple antibiotic resistance index (MARI) was calculated. Biofilm formation was assessed using the crystal violet assay. Bacterial growth was detected in 77.5% of samples. Isolates included Gram-positive cocci (32.25%), Gram-negative bacilli (22.59%), and Gram-positive bacilli (45.16%). MRSA was identified in 25.80% of isolates, and 70.97% showed alpha-hemolysis. The highest antibiotic resistance was observed against cefotaxime (41.93%), while susceptibility was noted for ciprofloxacin, tetracycline, amikacin, and gentamicin. The pharmaceutical-grade H. perforatum extract showed antibacterial activity (51.61%) and antibiofilm inhibition (60.23%). The market extract exhibited lower antibacterial activity (35.48%) but higher antibiofilm activity (87.55%). These results demonstrate that antibacterial effects on planktonic cells and antibiofilm activity are distinct properties, as stronger growth inhibition did not necessarily correspond to greater biofilm inhibition. The findings suggest that H. perforatum extracts may help control bacterial growth and biofilm formation on cosmetic tools.