Comparison of the Effects of Human β-defensin 3, Vancomycin, and Clindamycin on Staphylococcus aureus Biofilm Formation

Despite improvements in surgical techniques and implant design in orthopedic surgery, implantation-associated infections are still a challenging problem for surgeons. In 2006, trace quantities of human beta-defensin 3 (hBD-3) were found in human bone tissue and bone cells. Human beta-defensin 3 is a 45-amino-acid peptide that is considered the most promising class of defensin antimicrobial peptides and may help in the prevention and treatment of implantation-associated infections. Studies of the effectiveness of hBD-3 against Staphylococcus aureus showed that hBD-3 was more potent at low concentrations than other antibiotics. The effect of hBD-3 on S aureus biofilms has not been reported. We studied the effect of hBD-3, vancomycin, and clindamycin on S aureus biofilms and on the survival of the bacteria in the biofilms. Staphylococcus aureus biofilms were examined with confocal scanning laser microscopy. Staining with LIVE/DEAD BacLight viability stain (Molecular Probes Europe BV, Leiden, The Netherlands) differentiated between live and dead bacteria within the biofilms, and extracellular polymeric substances (slime) from the biofilms was evaluated after staining with calcofluor white (Sigma Chemical Company, Rocky Hill, New Jersey). Human beta-defensin 3 and clindamycin reduced the S aureus biofilm area. Human beta-defensin 3 was significantly more effective against bacteria from the S aureus biofilms than was clindamycin. Vancomycin did not reduce the S aureus biofilm area.