title: Impact of silver-containing wound dressings on bacterial biofilm viability and susceptibility to antibiotics during prolonged treatment.
abstract: The long-term antimicrobial efficacy of silver dressings against bacterial biofilms was investigated in a 7-day treatment in vitro model where the protein-rich medium was refreshed daily in order to mimic the conditions found in a wound bed. The use of plate-to-plate transfer assays demonstrated measurable differences in the effectiveness of several silver dressings on the viability of biofilm bacteria and their susceptibility to antibiotics. Whereas after the first day of treatment, all dressings used resulted in a significant reduction in the number of viable cells in the biofilms and disruption of the biofilm colonies, during prolonged treatment, the efficacy of dressings with hydrophilic base materials diminished with daily transfers, and bacterial populations recovered. For dressings with hydrophobic base materials, the level of efficacy correlated with the silver species loaded. Biofilm bacteria, which survived the initial silver treatment, were susceptible to tobramycin, ciprofloxacin, and trimethoprim-sulfamethoxazole, in contrast to untreated biofilms, which were highly tolerant to the same antibiotics. This acquired susceptibility was unaffected by the longevity of pretreatment with the silver dressings but depended on the dressing used. The antimicrobial efficacy of the dressings correlated with the type of the dressing base material and silver species loaded.
authors.affiliation: Calgary Center for Innovative Technology, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
authors.forename: Victoria
authors.initials: V
authors.lastname: Kostenko
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Lyczak
authors.forename: Katherine
authors.initials: K
authors.lastname: Turner
authors.forename: Robert John
authors.initials: RJ
authors.lastname: Martinuzzi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001458:Bandages / Q000382:microbiology*; D018441:Biofilms / Q000187:drug effects*; D002939:Ciprofloxacin / Q000627:therapeutic use; D050296:Microbial Viability / Q000187:drug effects; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D018030:Silver Compounds / Q000494:pharmacology*; D013997:Time Factors; D014031:Tobramycin / Q000494:pharmacology; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000494:pharmacology; D014946:Wound Infection / Q000382:microbiology / Q000517:prevention & control
chemical_list: D000900:Anti-Bacterial Agents; D018030:Silver Compounds; D002939:Ciprofloxacin; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D014031:Tobramycin