Activity of sodium metabisulfite against planktonic and biofilm Staphylococcus species

Biofilm-forming staphylococci cause a majority of intravascular catheter-related infections. We evaluated the effect of sodium metabisulfite, a preservative commonly added to intravenously administered pharmaceuticals as an antioxidant and previously used as a catheter lock solution, on planktonic and biofilm staphylococci at clinically encountered concentrations. Sodium metabisulfite exhibited bactericidal activity against planktonic Staphylococcus aureus, Staphylococcus lugdunensis, and Staphylococcus epidermidis at concentrations of 512, 512, and 1024 μg/mL, respectively. A concentration of 720 μg/mL inhibited cell growth by all 3 species in a biofilm formation assay. However, established S. aureus and S. lugdunensis biofilms showed less than 1.5 log₁₀ decreases in viable cell counts when treated with 720 μg/mL of sodium metabisulfite for 24 h. These in vitro results suggest that the use of sodium metabisulfite as a catheter lock may inhibit staphylococcal colonization of catheters, thereby preventing catheter-related infection.