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Potential bacterial contamination of eyedrops used for tonometry
R Palmberg1, Y S Gutierrez, D Miller
1Bascom Palmer Eye Institute, Department of Ophthalmology, University of Miami School of Medicine, Florida.
Abstract:
We compared the potential for bacterial contamination of a proparacaine hydrochloride solution preserved with benzalkonium chloride, which is used with fluorescein paper for tonometry, to that of a fluorescein-benoxinate hydrochloride combination solution preserved with chlorobutanol. We contaminated bottles of each solution with Pseudomonas aeruginosa or Staphylococcus aureus (10(7) organisms per milliliter of eyedrop solution). From the fluorescein-benoxinate hydrochloride solution, Staphylococcus organisms were cultured in declining numbers over time, with a half-life of nine seconds, and no Staphylococcus organisms were recovered after five minutes. Pseudomonas organisms disappeared from this solution within 15 seconds. Neither species was viable after 15 seconds in the proparacaine hydrochloride solution. Additionally, we cultured 12 bottles of fluorescein-benoxinate hydrochloride and 15 bottles of proparacaine hydrochloride that had been in use in the clinic for one month. No organisms were recovered from a drop dispensed from any bottle or from the tips, caps, rims, or solution from within any bottle, except that five colonies of Staphylococcus grew from the external rim of one bottle. We conclude that both solutions sterilize themselves rapidly and effectively. Either may be used safely for tonometry.
Insights
Both proparacaine hydrochloride and fluorescein-benoxinate hydrochloride eye solutions effectively prevent bacterial contamination. Studies show rapid self-sterilization, ensuring safety for tonometry procedures.
Area of Science:
- Ophthalmology
- Microbiology
- Pharmaceutical Science
Background:
- Ophthalmic solutions require effective preservation against microbial contamination.
- Proparacaine hydrochloride and fluorescein-benoxinate hydrochloride are commonly used topical anesthetics for tonometry.
Purpose of the Study:
- To compare the antimicrobial efficacy of proparacaine hydrochloride preserved with benzalkonium chloride against fluorescein-benoxinate hydrochloride preserved with chlorobutanol.
- To assess the safety of these solutions for use in tonometry.
Main Methods:
- Bacterial contamination challenge with Pseudomonas aeruginosa and Staphylococcus aureus.
- In vitro antimicrobial activity testing of both solutions.
- Clinical evaluation of in-use bottles for microbial recovery.
Main Results:
- Both Pseudomonas and Staphylococcus were rapidly eliminated from proparacaine hydrochloride solution within 15 seconds.
- Staphylococcus and Pseudomonas showed rapid clearance from fluorescein-benoxinate hydrochloride solution, with half-lives of 9 and 15 seconds respectively.
- No significant microbial contamination was found in clinical samples of either solution after one month of use.
Conclusions:
- Both proparacaine hydrochloride and fluorescein-benoxinate hydrochloride solutions exhibit rapid and effective self-sterilizing properties.
- The preservatives benzalkonium chloride and chlorobutanol ensure the microbial safety of these ophthalmic solutions.
- Both solutions can be safely utilized for tonometry procedures without risk of bacterial contamination.