title: Evaluation of spontaneous contamination of ocular medications.
abstract: BACKGROUND
  In order to evaluate whether single-dose ophthalmic preparations in 0.5-ml containers can safely be used within 24 h after the first opening, eigth different sterile ocular medications containing timolol, jaluronic acid, diclofenac, ketotifen, pilocarpine, formocortal, formocortal-gentamycin, and tetryzoline-feniramine (Farmigea, Italy) were opened and tested for spontaneous bacterial contamination after exposure to air.
  
  
  METHODS
  Samples (10 microl) were collected from exposed ophthalmic preparations after 0, 2, 4, 8 and 24 h.
  
  
  RESULTS
  No viable microorganisms were detected during and at the end of the evaluation period. In order to assess whether the resident or pathogenic ocular bacterial population due to repeated handling might contaminate the medications, about 10(5) cells of different species (Staphylococcus aureus, coagulase-negative staphylococci, Streptococcus pneumoniae, Streptococcus spp., Corynebacterium spp., Pseudomonas aeruginosa, Neisseria spp., Acinetobacter spp., Haemophilus influenzae, Escherichia coli and Candida albicans) were added to the containers and incubated at 37 degrees C or at room temperature. Samples were collected and the number of viable bacteria was estimated. The antibacterial effect of the ophthalmic compounds varied depending on the species considered. Tetryzoline-feniramine, pilocarpine, ketotifen and formocortal-gentamycin exhibited a frank bactericidal activity (<100 survivors after 18-24 h of exposure) against the great majority of the species tested.
  
  
  CONCLUSIONS
  These results indicate that the risk of spontaneous contamination of ophthalmic preparations after their first opening is low, and that all preparations tested exhibit an aspecific antibacterial activity. As a consequence, the safe usage of these ocular medications could be extended from the recommended 3 h to at least 24 h after the first usage.
authors.affiliation: Institute of Microbiology 'C.A. Romanzi', University of Genoa School of Medicine, Genoa, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Marchese
authors.forename: M
authors.initials: M
authors.lastname: Bozzolasco
authors.forename: L
authors.initials: L
authors.lastname: Gualco
authors.forename: G C
authors.initials: GC
authors.lastname: Schito
authors.forename: E A
authors.initials: EA
authors.lastname: Debbia
mesh_terms: D000287:Administration, Topical; D004340:Drug Contamination / Q000517:prevention & control*; D008826:Microbial Sensitivity Tests; D009883:Ophthalmic Solutions / Q000592:standards*
chemical_list: D009883:Ophthalmic Solutions