Abstract
Extracellular DNA is an adhesive component of staphylococcal biofilms. The aim of this study was to evaluate the antibiofilm activity of recombinant human DNase I (rhDNase) against Staphylococcus aureus and Staphylococcus epidermidis. Using a 96-well microtiter plate crystal-violet binding assay, we found that biofilm formation by S. aureus was efficiently inhibited by rhDNase at 1-4 μg l⁻¹, and preformed S. aureus biofilms were efficiently detached in 2 min by rhDNase at 1 mg l⁻¹. Pretreatment of S. aureus biofilms for 10 min with 10 mg l⁻¹ rhDNase increased their sensitivity to biocide killing by 4-5 log units. rhDNase at 10 mg l⁻¹ significantly inhibited biofilm formation by S. epidermidis in medium supplemented with sub-MICs of antibiotics. We also found that rhDNase significantly increased the survival of S. aureus-infected Caenorhabditis elegans nematodes treated with tobramycin compared with nematodes treated with tobramycin alone. We concluded that rhDNase exhibits potent antibiofilm and antimicrobial-sensitizing activities against S. aureus and S. epidermidis at clinically achievable concentrations. rhDNase, either alone or in combination with antimicrobial agents, may have applications in treating or preventing staphylococcal biofilm-related infections.