Staphylococcus epidermidis has emerged as a major nosocomial pathogen that is often associated with
infections of indwelling medical devices. Microbial adhesion to implanted foreign materials is a prerequisite for establishing
infection. We studied the time-dependent anti-adhesion effects of
linezolid and
vancomycin on three S. epidermidis clinical isolates. Minimum inhibitory concentration (MIC) values were identical for both agents for all three isolates (2 mg/l). Bacterial
suspensions were added to
polystyrene wells and treated with 0.5-4 times the MIC of
linezolid or
vancomycin at 0, 2, 4 or 6 h post-inoculation. Supra-inhibitory (2 and 4 x MIC) and inhibitory (MIC) concentrations of
linezolid demonstrated potent anti-adhesion activity following 2 and 4 h deferred treatments. Even at sub-inhibitory concentrations (0.5 x MIC), suppression of staphylococcal adherence to
polystyrene was still evident in most cultures.
Linezolid at two and four times the MIC also exerted significant inhibitory effects in cultures that had been treated with a 6-h delay. Supra-inhibitory and inhibitory concentrations of
vancomycin administered 2 h post-
infection appeared equally effective as
linezolid. However, sub-inhibitory concentrations of
vancomycin showed minimal or no activity against bacterial adhesion. When
vancomycin treatments were delayed by 4 h, only concentrations above the MIC prevented adherence.
Linezolid has promising in vitro anti-adhesion activity that merits further studies to determine its role in the management of
foreign-body infections.