The effects of copper additives on the quantity and cell viability of adherentStaphylococcus epidermidisin silicone implants

Abstract

This in vitro study evaluated the antibacterial effect of copper additives in silicone implants. Specimens of a standard silicone material used in breast augmentation and modified copper-loaded silicone specimens were prepared and incubated in a Staphylococcus epidermidis suspension (2 h, 37 degrees C). After the quantification of adhering staphylococci using a biofluorescence assay (Resazurin), the viability of the adhering bacterial cells was quantified by live or dead cell labeling in combination with fluorescence microscopy. In the Resazurin fluorometric quantification, a higher amount of adhering S. epidermidis cells was detected on pure silicone (4612 [2319/7540] relative fluorescence units [rfu]) than on silicone with copper additives (2701 [2158/4153] rfu). Additionally, a significantly higher amount of adhering bacterial cells (5.07% [2.03%/8.93%]) was found for pure silicone than for silicone with copper additives (1.72% [1.26%/2.32%]); (p < 0.001). Calculations from live or dead staining showed that the percentage of dead S. epidermidis cells adhered on pure silicone (52.1%) was significantly lower than on silicone with copper additives (79.7%); (p < 0.001). In vitro, silicone material with copper additives showed antibacterial effects against S. epidermidis. Copper-loaded silicone may prevent bacterial colonization, resulting in lower infection rates of silicone implants.

Effectiveness of antibacterial copper additives in silicone implants

“…Therefore, we applied fluorescence microscopy for directly monitoring bactericidal and anti-adhesive effects of copper-loaded substrata on the surface of the material. 31,39 Nevertheless, this study confirmed our previous findings, 26 i.e. no concentration-dependent effects could be found.…”

“…47,48 After different aging durations, implants were incubated with a human isolate of S. epidermidis to imitate the natural contamination of silicone specimens for our in vitro study, a method that has proven to be valuable before. 26,49,50 Surprisingly, the findings of this study suggest that artificial aging does not affect R a and SFE of silicone specimens. The lack of change of surface characteristics due to artificial aging is rather striking as, for example, very resistant and hard-wearing dental materials have shown evident changes after the process of artificial aging.…”

“…A strong correlation between the degree of a capsular contracture and the amount of bacterial colonisation could also be shown, and S. epidermidis was the most commonly found bacteria. 6,13,27,[42][43][44][45][46] Based on the results of our previous study evaluating the bactericidal effect of a newly invented copper-loaded coating on silicone breast implants, 26 we investigated the effect of coatings with different copper concentrations on the adherence and viability of S. epidermidis. The surface characteristics of the coated silicone specimens before and after different durations of artificial aging were characterised in defining SFE and R a .…”

“…13,24 In previous studies, copper has proven to be effective in reducing the cell viability of staphylococci 25 and in addition to the antibacterial effect against S. epidermidis in decreasing the amount of adhering bacteria on silicone surfaces. 26,27 Copper was chosen because comparing growth inhibition tests with tissue cells and bacteria showed copper to be by far the best compromise between antibacterial effectiveness and cytotoxicity. 27 For confirming the findings by Heidenau and for ascertaining the biocompatibility of our copper-loaded coatings, we conducted resazurin cell viability assay with mammalian cells.…”

Recent Developments in the Preparation of Silicones with Antimicrobial Properties

“…Silver,avery important antimicrobiala gent, was also incorporated by several researchers. [18d, 34] As ac omplementt os ilver, Gosau et al [35] workedw ith copperadditives.…”