title: Inhibitory Effects of 2,2'-Dipyridyl and 1,2,3,4,6-Penta-O-Galloyl-b-D-Glucopyranose on Biofilm Formation in Contact Lens Cases.
abstract: OBJECTIVE
  This study observed biofilm formation by Pseudomonas aeruginosa and Staphylococcus aureus in contact lens cases and investigated the inhibitory effects of 2,2'-dipyridyl (2DP) and 1,2,3,4,6-penta-O-galloyl-b-D-glucopyranose (PGG).
  
  
  METHODS
  Biofilm formation of P. aeruginosa ATCC 9027 and S. aureus ATCC 25923 and ATCC 6538 in contact lens cases was determined for a range of initial inocula and incubation times using crystal violet staining. The effects of 2DP and PGG on biofilm were evaluated alone and in combination by their incorporation into the media at commencement of incubation.
  
  
  RESULTS
  At 24 hours, biofilm production was related to initial concentration. However, with extended incubation, higher initial concentrations affected formation in S. aureus. Presence of 312 μM 2DP significantly inhibited P. aeruginosa biofilm formation, but had little effect on that of S. aureus. In contrast, PGG (50 μM) inhibited S. aureus biofilm formation, but had much less effect on that of P. aeruginosa. Combination of the agents effectively inhibited biofilm formation of all three organisms throughout a week-long incubation period with OD levels barely exceeding cell-free controls.
  
  
  CONCLUSIONS
  Biofilm formation of P. aeruginosa could be prevented by 2DP, while biofilm formation of S. aureus was inhibited by PGG. However, combining these agents showed better inhibition of biofilm production than use of either agent alone on both species. This combination may be useful in prevention of biofilm in contact lens cases, thereby reducing infection risk due to poor compliance with lens case cleaning and replacement. Further work is needed to confirm compatibility with multipurpose solutions and investigate cytotoxicity to ocular tissues.
authors.affiliation: School of Optometry The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong 2Squina Centre for Infection Control, School of Nursing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Pauline
authors.initials: P
authors.lastname: Cho
authors.affiliation: School of Optometry The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Guang-Sen
authors.initials: GS
authors.lastname: Shi
authors.affiliation: Squina Centre for Infection Control, School of Nursing, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
authors.forename: Maureen
authors.initials: M
authors.lastname: Boost
mesh_terms: D015082:2,2'-Dipyridyl / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D018639:Contact Lens Solutions / Q000494:pharmacology; D003261:Contact Lenses / Q000382:microbiology*; D015818:Eye Infections, Bacterial / Q000382:microbiology / Q000517:prevention & control*; D006801:Humans; D047348:Hydrolyzable Tannins / Q000494:pharmacology*; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors
chemical_list: D018639:Contact Lens Solutions; D047348:Hydrolyzable Tannins; C435084:pentagalloylglucose; D015082:2,2'-Dipyridyl; D000254:Sodium-Potassium-Exchanging ATPase