In vitro influence of vancomycin on adhesion of a Staphylococcus epidermidis strain encoding intercellular adhesion locus ica to intraocular lenses

Abstract

Purpose: To assess anti-adhesion and/or bactericidal properties of vancomycin in vitro and to determine when these effects are detectable to estimate its relevance to perioperative antibiotic prophylaxis and analyze the efficacy of a newly designed vancomycin insert prototype for endophthalmitis prevention.

Setting: University research laboratory, Lyon, France.

Methods: Staphylococcus epidermidis clinical strain N890074 containing the intercellular adhesion locus ica was used as the infectious agent. Vancomycin was used at 20 microg/mL. A sterile biocompatible, biodegradable vancomycin insert, releasing 230 microg of antibiotics over 100 minutes, was designed especially for this study. To obtain bacterial killing curves, experiments were first performed in a 103 colony-forming units (CFU/mL) bacterial suspension containing no intraocular lenses (IOL). Then IOLs were incubated in the suspension, and bacterial adherence was determined using bacterial counting with and without antibiotic.

Results: Vancomycin (solution and insert) had an anti-adhesion effect after 1 hour and a relevant bactericidal effect after 6 hours of incubation.

Conclusions: Vancomycin used with irrigating solutions does not remain in the anterior chamber long enough to develop bactericidal effect. Even if it initially reduces bacterial adhesion, used at a drug level dropping below the bacterial minimal inhibitory concentration, it could result in a secondary increase of the adhesion of slime-producing bacteria. A sufficiently high concentration was obtained in vitro by the new sustained-release system, thereby overcoming the theoretical drawback of a short half-life within the anterior chamber. Anti-adhesion and bactericidal action of vancomycin inserts remains to be confirmed in clinical studies.