title: In vitro efficacy of bismuth thiols against biofilms formed by bacteria isolated from human chronic wounds.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the antimicrobial efficacy of thirteen bismuth thiol preparations for bactericidal activity against established biofilms formed by two bacteria isolated from human chronic wounds.
  
  
  METHODS
  Single species biofilms of a Pseudomonas aeruginosa or a methicillin-resistant Staphylococcus aureus were grown in either colony biofilm or drip-flow reactors systems. Biofilms were challenged with bismuth thiols, antibiotics or silver sulfadiazine, and log reductions were determined by plating for colony formation.
  
  
  CONCLUSIONS
  Antibiotics were ineffective or inconsistent against biofilms of both bacterial species tested. None of the antibiotics tested were able to achieve >2 log reductions in both biofilm models. The 13 different bismuth thiols tested in this investigation achieved widely varying degrees of killing, even against the same micro-organism in the same biofilm model. For each micro-organism, the best bismuth thiol easily outperformed the best conventional antibiotic. Against P. aeruginosa biofilms, bismuth-2,3-dimercaptopropanol (BisBAL) at 40-80 μg ml⁻¹ achieved > 7·7 mean log reduction for the two biofilm models. Against MRSA biofilms, bismuth-1,3-propanedithiol/bismuth-2-mercaptopyridine N-oxide (BisBDT/PYR) achieved a 4·9 log reduction.
  
  
  CONCLUSIONS
  Bismuth thiols are effective antimicrobial agents against biofilms formed by wound bacteria and merit further development as topical antiseptics for the suppression of biofilms in chronic wounds.
authors.affiliation: Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA  Microbion Corporation, Bozeman, MT, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Folsom
authors.forename: B
authors.initials: B
authors.lastname: Baker
authors.forename: P S
authors.initials: PS
authors.lastname: Stewart
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects*; D001729:Bismuth / Q000494:pharmacology*; D004112:Dimercaprol / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects*; D050296:Microbial Viability; D009942:Organometallic Compounds / Q000494:pharmacology; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D013438:Sulfhydryl Compounds / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; C103324:bismuth dimercaptopropanol; D004112:Dimercaprol; D001729:Bismuth