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Viability of bacteria in glycerin and ethanol preserved sclera
1Department of Ophthalmology, Penn State University College of Medicine, Hershey 17033.
Background:
Sclera is commonly preserved in glycerin or ethanol before being used for ophthalmic surgery. The purpose of this study was to determine the ability of bacteria to survive in sclera preserved in glycerin or ethanol.
Methods:
Fresh sclera was inoculated with Staphylococcus aureus, Streptococcus pneumoniae, or Pseudomonas aeruginosa and transferred to preservative vials containing glycerin, 95% ethanol, or trypticase soy broth (control) and stored at room temperature. Pieces of sclera were removed from preservative at designated intervals over a 14-day period. The sclera was then homogenized, plated on blood agar, and incubated at 37 degrees C. Colonies were counted at 24, 48, and 72 hours.
Results:
S. pneumoniae, P. aeruginosa, and S. aureus were recovered from glycerin preserved sclera for up to 12 hours, 1.5 days, and 8 days, respectively. No bacteria was recovered from the ethanol preserved sclera.
Conclusions:
Bacteria cannot be recovered from ethanol preserved sclera but can survive in glycerin preserved sclera for at least 8 days. Ethanol may offer advantages over glycerin as a scleral preservative due to its greater antibacterial activity.