Catheter lock technique: in vitro efficacy of ethanol for eradication of methicillin-resistant staphylococcal biofilm compared with other agents

Biofilm formation in central venous catheters (CVC) is a prerequisite for catheter-related bloodstream infection (CRBSI). The catheter lock technique has been used to treat biofilm infection, but the ideal agent, concentration and the minimum exposure time necessary to eradicate the biofilms are not clearly known. In this study, biofilm-producing strains of staphylococci were used to find out the minimum biofilm eradication concentration of ethanol compared with three other conventional antibacterial agents. Eight representative methicillin-resistant staphylococci, from colonized CVCs, were studied. The biofilms were exposed to 1, 5 and 10 mg mL-1 of gentamicin, ciprofloxacin and vancomycin. The ethanol concentrations used were 20%, 40% and 80%. Biofilms were examined for the presence of live organisms after exposure to these agents from 30 min to 24 h. The three antibiotics were unable to eradicate the biofilms even after 24 h, while ethanol at 40% concentration could do so for all the isolates in 1 h. Our study highlights the efficacy and rationale of using 40% ethanol for a short period as catheter lock solution to eradicate biofilms and thus to prevent CRBSI, instead of using high concentrations of antibiotics for extended periods.