The effect of NucB on the prevention and dispersal of biofilms of clinical strains of Staphylococcus aureus and Staphylococcus epidermidis from prosthetic joint infections

Abstract

Total hip and knee replacements are one of the most common elective operations. Prosthetic joint infection (PJI) is a devastating and challenging complication. Often current antibiotic treatment is ineffective because PJI is commonly associated with biofilm formation. Prevention of biofilm attachment as well as disruption of established biofilms may therefore allow more effective treatment of such infections. NucB is a novel marine bacterial endonuclease, which degrades extracellular DNA, a structural component of biofilms and has shown promise in being able to degrade bacterial biofilms. The aim of this project was to investigate the effect of NucB on prevention of biofilm formation as well as dispersal of biofilms of clinical isolates of two important pathogens in PJI, Staphylococcus aureus and Staphylococcus epidermidis. In addition, enzyme activity against biofilms attached to surgically relevant surfaces such as titanium, polyethylene and cobalt chrome was quantified in order to understand how this enzyme would work on biofilms grown on surgically relevant surfaces. Biofilms were grown in microtiter plates and on metal and polyethylene discs and quantified using crystal violet staining as well as confocal microscopy. High purity NucB (>95%) was used. In the presence of low concentrations of NucB (1µg/ml), we observed between 34 and 76% inhibition of biofilm formation. NucB could also effectively disperse between 38 to 96% of biofilm attached to cobalt chrome, polyethylene, stainless steel and titanium surfaces. We also observed an increase in the ability of antibiotics to kill bacterial cells in the presence of NucB compared to controls. NucB can therefore successfully prevent the formation, and can disperse biofilms of clinical isolates of Staphylococcus aureus and Staphylococcus epidermidis. These results demonstrate a new approach to biofilm prevention and dispersal, and provide the foundation for the further development of NucB into a therapeutic product which could improve the treatment of PJI in the future