Background: Infection of intravascular or implanted biomedical devices often involves biofilm-forming staphylococci that are recalcitrant to antimicrobial therapy. The present study investigated the activity of 6 antimicrobial agents against biofilm-forming and non-biofilm-forming strains of staphylococci adherent to the surface of selected biomedical devices.
Methods: Five clinical staphylococcal strains were selected for study in (1) antibiotic-lock model (ALM) and (b) vascular graft model (Dacron and expanded polytetrafluoroethylene [ePFTE]) devices. Test strains were inoculated for 30 minutes to stabilize microbial adherence and then exposed to antibiotic; the impact on bacterial adherence was assessed at 1, 2, 4, 7, and 10 days.
Results: Regarding ALM, daptomycin and rifampin were effective at eradicating staphylococcal adherence by day 4 (P<.01); linezolid and gentamicin by day 7 (P<.01); vancomycin by day 7; and ceftriaxone failed to eradicate staphylococcal adherence in 4 of 5 strains by day 10. Regarding ePTFE, daptomycin and linezolid eradicated staphylococcal adherence by day 2 (P<.01); rifampin by day 4 (P<.01); vancomycin and gentamicin by day 7 (P<.01); and ceftriaxone failed to eliminate staphylococcal adherence in 3 of 5 strains by day 10. Regarding Dacron, daptomycin and rifampin eradicated adherent strains by day 4 (P<.01); linezolid by day 7 (P<.01), and vancomycin, gentamicin, and ceftriaxone decreased staphylococcal adherence by 90%, 95%, and 78%, respectively, by day 10.
Comments: Daptomycin, rifampin, and linezolid demonstrated greater efficacy and speed in eradicating microbial adherence of staphylococcal isolates from selected devices compared with vancomycin, gentamicin, or ceftriaxone (P<.01). Further studies are warranted, however, to validate the clinical efficacy of daptomycin and linezolid in the treatment of biomedical device-associated infections.