Microbial contamination of in-use ocular medications

Arch Ophthalmol. 1992 Jan;110(1):82-5. doi: 10.1001/archopht.1992.01080130084030.


Two hundred twenty in-use medications from 101 patients with nonmicrobial ocular surface disease were studied by culturing the bottle caps, a drop produced by simple inversion, and the interior contents removed sterilely. Conjunctival cultures were taken from these patients and 50 age-matched controls. Pathogenic organisms were harvested from conjunctivae significantly more frequently (P less than .01) from cases (34 of 101) than from controls (five of 50). Sixty-four medications (29%) had microorganisms cultured from at least one medication site. Gram-negative organisms were significantly more likely (P less than .00001) to be isolated from all medication sites than gram-positive organisms. Additionally, when isolated from medication sites, the gram-negative organisms were highly likely to be cultured from the conjunctiva as well. This was not true for pathogenic gram-positive organisms. We conclude that a cycle of contamination between in-use medications and conjunctivae may represent an important risk factor for microbial keratitis in patients with ocular surface disease.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Conjunctiva / microbiology
  • Drug Contamination*
  • Eye Diseases / microbiology*
  • Eye Infections / microbiology
  • Female
  • Fungi / isolation & purification
  • Gram-Negative Bacteria / isolation & purification*
  • Gram-Positive Bacteria / isolation & purification*
  • Humans
  • Male
  • Microbiological Techniques
  • Middle Aged
  • Ointments
  • Ophthalmic Solutions*


  • Ointments
  • Ophthalmic Solutions