Effects of Dermocosmetic Preservative Exposure on the Development of Antimicrobial Resistance in Skin Microbiota

Abstract

Background: Antimicrobial preservatives are an integral part of dermocosmetic formulations to prevent contamination and ensure product stability. Exposure to these substances may create selective pressure on the skin microbiota and may potentially lay the groundwork for the development of antimicrobial resistance. This study aimed to evaluate the effects of commonly used dermocosmetic preservatives on the resistance profiles of skin-associated microorganisms.

Methods: Staphylococcus aureus ATCC 6538, Staphylococcus epidermidis ATCC 35984, Pseudomonas aeruginosa ATCC 15442, and Candida albicans ATCC 14053 strains were exposed to phenoxyethanol, benzyl alcohol, potassium sorbate, sodium benzoate, and methylparaben for 5, 15, and 30 days. Minimum inhibitory concentration (MIC) values were determined at all stages using the broth microdilution method. Antimicrobial resistance was evaluated using vancomycin, cefepime, and fluconazole, respectively.

Results: Benzyl alcohol and methylparaben showed the highest initial activity against bacterial strains, whereas potassium sorbate exhibited lower efficacy. C. albicans generally showed higher susceptibility to preservatives. Prolonged preservative exposure led to time-dependent increases in antibiotic MIC values in S. epidermidis, P. aeruginosa, and C. albicans, while S. aureus remained largely stable. Twofold increases were observed in the early period (5-15 days), and these increases reached fourfold on day 30 in some preservative–microorganism combinations. The observed MIC increases remained at the threshold of clinical resistance limits.

Conclusion: Prolonged exposure to dermocosmetic preservatives may lead to measurable and time-dependent resistance developments reflecting adaptive microbial responses. These findings indicate that safety evaluations should consider not only the immediate antimicrobial efficacy of preservatives but also their long-term selective effects.

Cite this article as: Ayvaz AS, Öztürk Ş, Altanlar N. Effects of dermocosmetic preservative exposure on the development of antimicrobial resistance in skin microbiota. Trends in Pharmacy, 2026, 3, 0016, doi: 10.5152/TIP.2026.26016.