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We developed a highly efficient, biocompatible surface coating that disperses bacterial biofilms through enzymatic cleavage of the extracellular biofilm matrix. The coating was fabricated by binding the naturally existing enzyme dispersin B (DspB) to surface-attached polymer matrices constructed via a layer-by-layer (LbL) deposition technique. LbL matrices were assembled through electrostatic interactions of poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMAA), followed by chemical cross-linking with glutaraldehyde and pH-triggered removal of PMAA, producing a stable PAH hydrogel matrix used for DspB loading. The amount of DspB loaded increased linearly with the number of PAH layers in surface hydrogels. DspB was retained within these coatings in the pH range from 4 to 7.5. DspB-loaded coatings inhibited biofilm formation by two clinical strains of Staphylococcus epidermidis. Biofilm inhibition was ≥98% compared to mock-loaded coatings as determined by CFU enumeration. In addition, DspB-loaded coatings did not inhibit attachment or growth of cultured human osteoblast cells. We suggest that the use of DspB-loaded multilayer coatings presents a promising method for creating biocompatible surfaces with high antibiofilm efficiency, especially when combined with conventional antimicrobial treatment of dispersed bacteria.

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.

Widespread antibiotic resistance is a major incentive for the investigation of novel ways to treat or prevent infections. Much effort has been put into the discovery of peptides in nature accompanied by manipulation of natural peptides to improve activity and decrease toxicity. The ever increasing knowledge about bacteria and the discovery of quorum sensing have presented itself as another mechanism to disrupt the infection process. We have shown that the natural quorum sensing (QS) peptide, competence-stimulating peptide (CSP), used by the caries causing bacteria Streptococcus mutans when used in higher than normally present concentrations can actually contribute to cell death in S. mutans. Using an analogue of this quorum sensing peptide (KBI-3221), we have shown it to be beneficial at decreasing biofilm of various Streptococcus species. This chapter looks at a number of assay methods to test the inhibitory effects of quorum sensing peptides and their analogues on the growth and biofilm formation of oral bacteria.

Objectives: The objectives of this study were to examine: (i) synergy of the combination of triclosan and DispersinB (DspB); (ii) in vitro efficacy and durability of triclosan + DspB-coated vascular catheters; and (iii) in vivo efficacy of triclosan + DspB-coated catheters compared with chlorhexidine-silver sulfadiazine (CH-SS)-coated and uncoated (control) vascular catheters in preventing colonization by Staphylococcus aureus., Methods: We investigated the potential synergistic antimicrobial and antibiofilm activity of triclosan and DspB by biofilm assays. The in vitro antimicrobial efficacy of triclosan + DspB-coated catheters was determined by microbial colonization assays. Antimicrobial durability of the coated catheters was tested by soaking segments in bovine serum for 7 days and determining antimicrobial activity, and by a serial plate transfer method. The in vivo efficacy of triclosan + DspB-coated catheters compared with CH-SS-coated and uncoated catheters was assessed by subcutaneous implantation of segments in a rabbit model of S. aureus infection., Results: The combination of triclosan and DspB showed synergistic antimicrobial and antibiofilm activity against S. aureus, Staphylococcus epidermidis and Escherichia coli, significantly reduced bacterial colonization (P < 0.05) and generally demonstrated a prolonged superior antimicrobial activity against clinical pathogens compared with CH-SS-coated catheters. Triclosan + DspB-coated and CH-SS-coated catheters exhibited equal in vivo efficacy (P

Aims: To determine the effect of a composition comprising ovotransferrin (OT), protamine sulfate (PS) and ethylenediaminetetraacetic acid (EDTA) on biofilm formation by catheter-associated bacteria., Methods and Results: The in vitro activity of OT, PS and EDTA alone and in combinations against biofilm formation by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Enterococcus faecalis and Staphylococcus epidermidis was investigated. All the three compounds either alone or in combinations failed to inhibit the growth completely at the concentrations tested. However, the subinhibitory concentrations of three compounds in a composition showed synergistic inhibitory effect on biofilm formation by K. pneumoniae, Ps. aeruginosa and S. epidermidis. Furthermore, 79-95% reduction in Ps. aeruginosa and S. epidermidis biofilm formation was observed in a clear vinyl urinary catheter treated with the composition., Conclusion: The subinhibitory concentrations of OT, PS and EDTA in a composition were effective in reducing biofilm formation by catheter-associated bacteria., Significance and Impact of the Study: This study shows that a synergistic composition-comprising non-antibiotic generally regarded as safe (GRAS) compounds such as OT, PS and EDTA may be used in the prevention of catheter-related infections.