Effects of Cosmetic Preservatives on Healthy Facial Skin Microflora

The present study was designed to evaluate the effects of seven common preservatives used in Iranian cosmetic products on facial skin microflora.

Fifteen healthy volunteers, aged 20 to 35 years, were recruited. Three symmetrical sites from the cheeks of each volunteer were selected and samples were collected. DNA was extracted from the culture using the boiling method. The fungi's internal transcribed spacer (ITS) region was amplified using ITS1/ITS4 primers, for 16s to identify bacteria and Staphylococcus specific primers. The effects of the preservatives were assessed based on growth on broth culture media.

Primary identification was based on yeast on CHROM agar, in which 15 different yeasts were isolated; then, PCR was used to identified the species as: C. albicans (n: 14; 93%), C. orthopsilosis (n: 1; 7%). One primary identified yeast on Dixon media was precisely differentiated as M. furfur using the PCR method. Fifteen primary identified cocci on tryptic soy agar media were identified as Staphylococcus epidermis. All the preservatives showed to inhibit the growth of isolated fungi, but not that of bacterial microflora.

The present study showed preservatives in cosmetic products can alter skin microflora while also preventing the growth of pathogenic bacteria.