Effect of two cosmetic compounds on the growth, biofilm formation activity, and surface properties of acneic strains of Cutibacterium acnes and Staphylococcus aureus

Abstract

Increasing popularity of preservative-free cosmetics necessitates in-depth research, specifically as bacteria can react to local factors by important metabolic changes. In this respect, investigating the effect of cosmetic preparations on pathogenic strains of commensal species such as acneic forms of Cutibacterium acnes (former Propionibacterium acnes) and bacteria behaving both as commensals and opportunistic pathogens such as Staphylococcus aureus is of major interest. In this study, we studied the effect of commonly used cosmetics, Uriage^™ thermal water (UTW) and a rhamnose-rich polysaccharide (PS291^® ) on RT4 and RT5 acneic strains of C. acnes and a cutaneous strain of S. aureus. UTW affected the growth kinetic of acneic C. acnes essentially by increasing its generation time and reducing its biomass, whereas only the S. aureus final biomass was decreased. PS291 had more marginal effects. Both compounds showed a marked antibiofilm activity on C. acnes and S. aureus. For S. aureus that appeared essentially due to inhibition of initial adhesion. Cosmetics did not modify the metabolic activity of bacteria. Both C. acnes and S. aureus showed marked hydrophobic surface properties. UTW and PS291 had limited effect on C. acnes but increased the hydrophobic character of S. aureus. This work underlines the effect of cosmetics on cutaneous bacteria and the potential limitations of preservative-free products.

Keywords: Cutibacterium acnes; Staphylococcus aureus; biofilm; cosmetics; metabolism; surface adhesion; surface polarity.

Figure 1

Effect of thermal water and rhamnose‐rich polysaccharide (PS291^®) on the growth kinetics of acneic strains of Cutibacterium acnes and Staphylococcus aureus. (a) Effect of Uriage thermal water (UTW) and PS291^® on the growth kinetics of acneic strain of C. acnes RT4. (b) Effect of UTW and PS291^® on the growth kinetics of acneic strain of C. acnes RT5. (c) Effect of UTW and PS291^® alone or in association on the growth kinetics a cutaneous strain of S. aureus (MFP03). Physiological water (PS; NaCl 0.9%) and medium supplement with 4% water‐propanediol mixture were used as controls of UTW and PS291^®, respectively. Curves are the mean of three independent experiments. Statistical variability was minimal and error bars (SEM) do not appear in the figure

Figure 2

Effect of thermal water and rhamnose‐rich polysaccharide (PS291^®) on the biofilm formation activity of acneic strains of Cutibacterium acnes and Staphylococcus aureus. The effect of Uriage thermal water (UTW) and PS291^® on biofilm formation activity of acneic strains of C. acnes RT4 and 5 and of the cutaneous strain of S. aureus (MFP03) was measured by the crystal violet technique. Control studies were realized as indicated in Figure 1. All experiments were carried out in at least three replicates (*p < 0.05)

Figure 3

Effect of thermal water and rhamnose‐rich polysaccharide (PS291^®) on the structure of biofilms formed by the RT4 acneic strain of Cutibacterium acnes. Biofilm formation was monitored using Syto 9 green. Horizontal and transverse X/Z views were obtained and submitted to analysis. (a) Control initial cell adhesion after 2 hr. (b) Control biofilm after 72 hr. (c) Biofilm formed in the presence of PS 50%. (d) Biofilm formed in the presence of ETW 50%. (e) Biofilm formed in the presence of PS291 4%. All experiments were carried out in at least three replicates. Control studies were realized as indicated in Figure 1

Figure 4

Effect of thermal water and rhamnose‐rich polysaccharide (PS291^®) on the structure of biofilms formed by the RT5 acneic strain of Cutibacterium acnes. Biofilm formation was monitored using Syto 9 green. Horizontal and transverse X/Z views were obtained and submitted to analysis. (a) Control initial cell adhesion after 2 hr. (b) Control biofilm after 72 hr. (c) Biofilm formed in the presence of PS 50%. (d) Biofilm formed in the presence of ETW 50%. (e) Biofilm formed in the presence of PS291 4%. All experiments were carried out in at least three replicates. Control studies were realized as indicated in Figure 1

Figure 5

Effect of thermal water and rhamnose‐rich polysaccharide (PS291^®) on the structure of biofilms formed by the human skin strain Staphylococcus aureus MFP03. Biofilm formation was monitored using Syto 9 green. Horizontal and transverse X/Z views were obtained and submitted to analysis. (a) Control initial cell adhesion after 2 hr. (b) Control biofilm after 24 hr. (c) Biofilm formed in the presence of PS 50%. (d) Biofilm formed in the presence of UTW 50%. (e) Biofilm formed in the presence of PS291 4%. All experiments were carried out in at least three replicates. Control studies were realized as indicated in Figure 1

Figure 6

Effect of thermal water and rhamnose‐rich polysaccharide (PS291^®) on Staphylococcus aureus MFP03 microcolonies formation in dynamic conditions. In order investigate the equilibrium between planktonic and adherent bacteria, S. aureus MFP03 was incubated in microwells under agitation and microcolonies formation was monitored after 24 hr. (a) Structure of microcolonies formed in the absence of treatment and in the presence of PS 50%, UTW 50%, PS291 4% and UTW 50% + PS291 4%. (b) Mean number of microcolonies formed by S. aureus. All experiments were carried out in at least three replicates. Control studies were realized as indicated in Figure 1 (*p < 0.05)

Figure 7

Effect of thermal water and rhamnose‐rich polysaccharide (PS291^®) on the metabolic activity of an acneic strain of Cutibacterium acnes and Staphylococcus aureus in biofilms. The Effect of Uriage thermal water and PS291^® alone or in association on the metabolic activity of C. acnes RT4 and S. aureus MFP03 was measured by biofilm staining with 3‐(4, 5‐dimethyl‐2‐thiazolyl)‐2, 5‐diphenyl‐2H‐tetrazolium bromide (MTT). (a) C. acnes RT4. (b) S. aureus MFP03. All experiments were carried out in at least three replicates. Control studies were realized as indicated in Figure 1

Figure 8

Effect of thermal water and rhamnose‐rich polysaccharide on the affinity of acneics strains of Cutibacterium acnes and Staphylococcus aureus to solvents of different polarities. (a) C. acnes RT4. (b) C. acnes RT5. (c) S. aureus MFP03. chloroform (CH), hexadecane (HD), decane (De) and ethyl acetate (EA). Each value represents the M ± SEM of five independent experiments. Control studies were realized as indicated in Figure 1 (*p < 0.05)