title: Distribution and Inhibition of Liposomes on Staphylococcus aureus and Pseudomonas aeruginosa Biofilm.
abstract: BACKGROUND
  Staphylococcus aureus and Pseudomonas aeruginosa are major pathogens in chronic rhinosinusitis (CRS) and their biofilms have been associated with poorer postsurgical outcomes. This study investigated the distribution and anti-biofilm effect of cationic (+) and anionic (-) phospholipid liposomes with different sizes (unilamellar and multilamellar vesicle, ULV and MLV respectively) on S. aureus and P. aeruginosa biofilms.
  
  
  METHODS
  Specific biofilm models for S. aureus ATCC 25923 and P. aeruginosa ATCC 15692 were established. Liposomal distribution was determined by observing SYTO9 stained biofilm exposed to DiI labeled liposomes using confocal scanning laser microscopy, followed by quantitative image analysis. The anti-biofilm efficacy study was carried out by using the alamarBlue assay to test the relative viability of biofilm treated with various liposomes for 24 hours and five minutes.
  
  
  RESULTS
  The smaller ULVs penetrated better than larger MLVs in both S. aureus and P. aeruginosa biofilm. Except that +ULV and -ULV displayed similar distribution in S. aureus biofilm, the cationic liposomes adhered better than their anionic counterparts. Biofilm growth was inhibited at 24-hour and five-minute exposure time, although the decrease of viability for P. aeruginosa biofilm after liposomal treatment did not reach statistical significance.
  
  
  CONCLUSIONS
  The distribution and anti-biofilm effects of cationic and anionic liposomes of different sizes differed in S. aureus and P. aeruginosa biofilms. Reducing the liposome size and formulating liposomes as positively charged enhanced the penetration and inhibition of S. aureus and P. aeruginosa biofilms.
authors.affiliation: Department of Surgery- Otorhinolaryngology Head and Neck Surgery, The Queen Elizabeth Hospital, and the University of Adelaide, Adelaide, South Australia; The Rhinology Department, the First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Dong
authors.affiliation: Ian Wark Research Institute, University of South Australia, Mawson Lakes, South Australia.
authors.forename: Nicky
authors.initials: N
authors.lastname: Thomas
authors.affiliation: Ian Wark Research Institute, University of South Australia, Mawson Lakes, South Australia.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Thierry
authors.affiliation: Department of Surgery- Otorhinolaryngology Head and Neck Surgery, The Queen Elizabeth Hospital, and the University of Adelaide, Adelaide, South Australia.
authors.forename: Sarah
authors.initials: S
authors.lastname: Vreugde
authors.affiliation: Ian Wark Research Institute, University of South Australia, Mawson Lakes, South Australia.
authors.forename: Clive A
authors.initials: CA
authors.lastname: Prestidge
authors.affiliation: Department of Surgery- Otorhinolaryngology Head and Neck Surgery, The Queen Elizabeth Hospital, and the University of Adelaide, Adelaide, South Australia.
authors.forename: Peter-John
authors.initials: PJ
authors.lastname: Wormald
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D006801:Humans; D008081:Liposomes / Q000494:pharmacology*; D018613:Microscopy, Confocal; D010743:Phospholipids / Q000494:pharmacology; D011552:Pseudomonas Infections / Q000188:drug therapy; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000254:growth & development*; D013203:Staphylococcal Infections / Q000188:drug therapy; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development*
chemical_list: D000900:Anti-Bacterial Agents; D008081:Liposomes; D010743:Phospholipids