Bacterial contamination of ophthalmic solutions used in an extended care facility

To assess the frequency of contamination of ophthalmic solutions in a long-term care facility and to describe the characteristics of contaminated solutions.

One hundred and twenty-three ophthalmic solutions used for patient treatment in a long-term care facility were cultured for bacteria. The culture results were analysed according to the therapeutic class of the solution, how long the bottle had been in use and the appearance of the bottle on visual inspection.

10 (8%) of the 123 multiple-dose solutions were contaminated with bacteria: 4 (50%) of 8 steroid-containing anti-inflammatory solutions, 2 (33%) of 6 combination antimicrobial and steroid-containing anti-inflammatory solutions, 2 (6%) of 34 solutions for treatment of glaucoma, and 2 (4%) of 57 medications for "dry eye". None of the mydriatic, miotic or non-combination antimicrobial solutions was contaminated. Proteus mirabilis was identified in 8 (80%) of the 10 contaminated solutions. Only 30% of the contaminated solution bottles were classified as "dirty" bottles when the bottles were visually inspected. Neither the length of time the solutions had been in use nor the appearance of the bottle predicted contamination.

8% of ophthalmic solutions used in a long-term care facility were contaminated with bacteria, most frequently Proteus mirabilis. Compared with solutions not containing steroids, steroid solutions were 5.8 times more likely to be contaminated (RR = 5.84, 95% CI: 2.42 to 14.10, p<0.002). The frequent contamination during reuse of certain steroid-containing ophthalmic solutions raises the question of whether single-use solutions might be preferred for these and other classes of ocular drugs.