Comparison between in vitro activity of silver sulfadiazine alone and associated with hyaluronic acid against bacteria and fibroblasts

Aim. Pressure and burn ulcers easily undergo superinfection with bacteria colonizing the epidermis. Silver sulfadiazine (SS) 1% solution and silver sulfadiazine with 0.2% hyaluronic acid (SSHA) are considered the gold standard for topic treatment and prevention of bacterial superinfection. Methods. Staphylococcus aureus and Pseudomonas aeruginosa were used to determine the in vitro minimum bactericidal concentrations (MBCs) of these compounds, using broth dilution method and subculture onto agar. The potential effects of SS and SSHA upon cell proliferation (FP) was verified using primary human fibroblasts in vitro. Finally, suspensions of S. aureus and P. aeruginosa were examined by transmission electron microscope (TEM) at SS and SSHA MBCs.Results. MBCs of SS and SSHA were 1:10 (corresponding to 1 mg/mL of SS) and 1:5, respectively, towards all species and the variant tested. FP was significantly reduced by SS and SSHA, but the difference between the two substances was not significant. Bacteria treated with SS showed, at TEM examination, cell membrane alterations, cytoplasm vacuolization and intracytoplasm silver precipitates. Under the effect of SSHA, the bacterial alterations were similar, but less marked. Conclusion. SS showed an increased antibacterial activity respect to SSHA, as also confirmed by TEM. Fibroblast proliferation was decreased by both the compounds, but the difference between them was not significant.