Bacterial Contamination and Antimicrobial Resistance in Used Eye Cosmetic Products

Eye cosmetic products are widely used and applied in close proximity to the ocular surface, making their microbiological safety particularly important. The aim of this study was to assess bacterial contamination in used eye cosmetic products, characterize the antimicrobial resistance profiles of the isolated bacteria, and perform molecular genotypic analysis. A total of 71 samples, including mascara, eyeliner, and eyeshadow, were analyzed. Microbiological analysis revealed that Bacillus spp. and coagulase-negative staphylococci (CoNS) were the predominant microorganisms, while no major pathogens such as Staphylococcus aureus, Escherichia coli, or Pseudomonas aeruginosa were detected. Antimicrobial susceptibility testing demonstrated high susceptibility of isolates to gentamicin, vancomycin, and linezolid, whereas resistance to benzylpenicillin and clindamycin was observed among Staphylococcus spp. Molecular identification based on 16S rRNA gene sequencing confirmed the presence of Bacillus licheniformis, Bacillus subtilis, Staphylococcus epidermidis, and Staphylococcus warneri, with sequences showing high similarity to globally distributed strains. Although the detected microorganisms were predominantly opportunistic, their presence in products applied near the eyes suggests a potential risk of microbial transfer to the ocular surface. These findings highlight the importance of proper hygiene practices, regular product replacement, and effective quality control measures to minimize microbial contamination and associated health risks.