RESUMO
Vancomycin lock solution (LS) is recommended for the conservative treatment of subcutaneous injection port (SIP)-related infections, but may be associated with failure. We used an in vitro dynamic model of biofilm formation in an SIP, based on a continuous flow circulating via a real SIP, to assess the effectiveness of vancomycin (5 mg/ml), daptomycin (5 mg/ml) and ethanol 40 % LS in eradicating a pre-established Staphylococcus epidermidis biofilm. Heparin, Ringer's lactate and enoxaparin sodium LS were used as controls. The logarithmic reductions of colony-forming units (CFU) were compared by Student's t-test. After 24 h of exposure, the vancomycin LS did not exert a greater bactericidal effect than the heparin LS control (mean logarithmic reduction: 2.27 ± 0.58 vs. 1.34 ± 0.22, respectively, p = 0.3). The mean logarithmic reduction was greater with daptomycin LS (5.45 ± 0.14 vs. 0.39 ± 0.12, p < 0.01) and ethanol LS (6.79 ± 1.03 vs. 1.43 ± 0.54, p = 0.02). Bacterial revival after exposure to 24 h of LS was assessed. The mean viable bacteria count was significantly higher for vancomycin LS (9.36 ± 0.10 log(10)CFU) and daptomycin LS (9.16 ± 0.02 log(10)CFU) than for ethanol LS (2.95 ± 1.65 log(10)CFU). Ethanol appeared to be the most attractive option to treat SIP-related infection, but its poor ability to entirely disrupt the biofilm structure may require its use in association with a dispersal agent to avoid renewal of the biofilm.
