Abstract
Background
Staphylococcus epidermidis is one of the main organisms associated with prosthetic joint infections. One of the major pathogenic attributes of this organism is the ability to form biofilms, making it extremely resistant to currently available antimicrobial therapies. There is, therefore, an urgent requirement for novel agents that are effective against this organism. Antimicrobial peptides represent a novel group of agents that show good activity towards biofilm-forming S. epidermidis. Antimicrobial peptides are particularly interesting due to their multiple modes of action which are thought to reduce the rate of resistance development to the agents.
Aim
The aim of the current study was to assess the effect of antimicrobial peptides gallidermin and novel peptide NI01 on the growth of reference and clinical isolates of S. epidermidis on polymethylmethacrylate (PMMA) cement following incorporation of the peptides.
Methods
To do this a novel biofilm flow-through model was used to determine the effect of the peptides on growth of the strains, allowing the assessment of planktonic and biofilm cells. The antimicrobial peptides were incorporated into 4mm diameter PMMA beads (1% w/w) created using a specially developed poly (tetrafluoroethylene) (PTFE) mould.
Results
10 beads were used per housing unit for each of the different treatments. Each of the 10 beads was inoculated with 6 × 108 cfu/ml of S. epidermidis reference strain RP62a and clinical isolates 53 and 156. The growth of the strains was then monitored over a period of five days and the effect of the peptides assessed. Results identified both gallidermin and NI01 caused a significant decrease in the growth of S. epidermidis reference strain RP62a and clinical isolates 53 and 156 (P=< 0.05).
Conclusion
This study identifies the effectiveness of antimicrobial peptides gallidermin and novel antimicrobial peptide NI01 against biofilm forming S. epidermidis and highlights their potential use in the orthopaedic setting.
