title: Pseudomonas aeruginosa growth in Refresh Plus®.
abstract: OBJECTIVE
  To assess Pseudomonas aeruginosa growth in Refresh Plus(®), a unit-dose preservative-free ophthalmic solution indicated for the treatment of dry eye and after laser-assisted in situ keratomileusis (LASIK) surgery, which contains carboxymethylcellulose 0.5% as its active ingredient.
  
  
  METHODS
  Multiple test tubes of Refresh Plus were inoculated with 3 clinical ocular isolates of P. aeruginosa to achieve a target concentration of ∼100 colony-forming units (CFU)/mL. The tubes were incubated at 25°C and samples were aseptically removed at 6, 12, and 24 h. The samples were cultured to enumerate the population at each time point.
  
  
  RESULTS
  After 6 h incubation, the number of CFU/mL was 3,200 for isolate 1, 2,000 for isolate 2, and 6,480 CFU/mL for isolate 3. For all 3 organisms tested, the number of CFU/mL after 12 and 24 h incubation was >10(6) CFU/mL.
  
  
  CONCLUSIONS
  Under the conditions of this experiment, Refresh Plus appears to support P. aeruginosa growth, suggesting that if the solution in a unit-dose vial of Refresh Plus were contaminated with P. aeruginosa during use, the organism would survive and replicate in the solution over time. Noncompliance with the manufacturer's recommendations (i.e., reuse of an open vial) may result in contamination of the solution with P. aeruginosa, which may cause severe keratitis.
authors.affiliation: Section of Ophthalmology, Department of Surgery, Microsurgery, and Medico-surgical Specialties, University of Sassari, Sassari, Italy. apinna@uniss.it
authors.forename: Antonio
authors.initials: A
authors.lastname: Pinna
authors.forename: Donatella
authors.initials: D
authors.lastname: Usai
authors.forename: Stefania
authors.initials: S
authors.lastname: Zanetti
mesh_terms: D002266:Carboxymethylcellulose Sodium / Q000008:administration & dosage / Q000737:chemistry / Q000592:standards* / Q000627:therapeutic use; D004340:Drug Contamination; D016503:Drug Delivery Systems; D015352:Dry Eye Syndromes / Q000188:drug therapy / Q000209:etiology; D006801:Humans; D007634:Keratitis / Q000382:microbiology; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects; D009883:Ophthalmic Solutions / Q000008:administration & dosage / Q000737:chemistry / Q000592:standards* / Q000627:therapeutic use; D011310:Preservatives, Pharmaceutical; D011550:Pseudomonas aeruginosa / Q000254:growth & development*
chemical_list: D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical; D002266:Carboxymethylcellulose Sodium