EFFECT OF SURFACE MODIFICATIONS OF INTRAOCULAR LENSES ON THE ADHERENCE OF STAPHYLOCOCCUS-EPIDERMIDIS

The development of polymers with different surface properties and surf ace modifications of intraocular lenses (IOL) should reduce foreign bo dy reactions after implantation by reducing the surface hydrophobicity of the lenses. It was examined how far such surface variations influe nced the adhesiveness of bacteria. The most common organism isolated f rom cases of postoperative endophthalmitis is Staphylococcus epidermid is. For this reason, three strains of this species, the type strain AT CC 14990 and two clinical isolates (8687, 6579 I), with different hydr ophobic surfaces, were studied. IOL made of PMMA, silicone, and a copo lymer as well as PMMA lenses with modified surfaces (unpolished, polis hed, silanized, and heparinized) were used. Bacteria were radiolabelle d with H-3-thymidine and the adherent bacteria were calculated per mm( 2) of lens surface. The three strains adhered better to the unpolished surface of silicone than to PMMA. Treatment of PMMA surface by polish ing diminished the differences between the strains. An influence of hy drophobic interactions on the adherence of S. epidermidis ATCC 14990 w as demonstrated. The adherence of this hydrophobic type strain was cle arly reduced by heparinization of the PMMA surface. In contrast, the h ydrophilic catheter isolate 6579 I adhered better to modified surfaces . This strain differed clearly in its PFGE pattern from both hydrophob ic strains. Hydrophobic interactions play a role in the bacterial adhe rence to intraocular lenses in vitro and in vivo. Modifications of pol ymer surfaces, however, can result in rather different effects dependi ng on the bacterial surface composition and properties.