title: Survival of contaminating bacteria in over-the-counter artificial tears.
abstract: BACKGROUND
  The use of OTC artificial tears is becoming increasingly widespread. Unintentional contamination of artificial tear products potentiates a risk of developing bacterial keratitis or exacerbating an existing eye infection. Presently, no published study has investigated recovery from bacterial contamination of artificial tear products.
  
  
  METHODS
  Four different over-the-counter (OTC) artificial tear products were contaminated with two types of bacteria. Staphylococcus aureus and pseudomonas aeruginosa were analyzed for the survivability of the microorganisms at various times following contamination.
  
  
  RESULTS
  In this cross-sectional study, it was found that all the preserved brands showed a significant recovery rate from contamination compared to the preservative-free brand. After 9 hours, the preservative-free brand did not completely regain sterility after contamination with either bacteria.
  
  
  CONCLUSIONS
  This study indicates that preserved artificial tears recover from bacterial contamination at a significantly faster rate than preservative-free products. It is likely that the recovery from bacterial contamination is not solely attributed to the preservative, but that other variables may contribute.
authors.affiliation: School of Optometry, University of California, Berkeley 94720, USA.
authors.forename: M G
authors.initials: MG
authors.lastname: Harris
authors.forename: A
authors.initials: A
authors.lastname: Gee
authors.forename: R
authors.initials: R
authors.lastname: Kusumoto
authors.forename: H
authors.initials: H
authors.lastname: Lee
mesh_terms: D015169:Colony Count, Microbial; D003430:Cross-Sectional Studies; D004340:Drug Contamination; D004366:Nonprescription Drugs; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical; D011550:Pseudomonas aeruginosa / Q000302:isolation & purification / Q000502:physiology*; D013211:Staphylococcus aureus / Q000302:isolation & purification / Q000502:physiology*
chemical_list: D004366:Nonprescription Drugs; D009883:Ophthalmic Solutions; D011310:Preservatives, Pharmaceutical