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Survival of streptococcus in optisol-GS medium
A C Varner1, L F Rich, B L Crow
1Casey Eye Institute, OHSU, Portland 97201, USA.
Summary
Donor corneas contaminated with Enterococcus faecium can resist standard antibiotic preservation. This highlights potential risks of endophthalmitis following penetrating keratoplasty, even with OptiSol-GS medium.
Area of Science:
- Ophthalmology
- Microbiology
- Transplantation
Background:
- Donor cornea contamination is a significant risk factor for endophthalmitis after penetrating keratoplasty.
- OptiSol-GS corneal storage medium contains gentamicin and streptomycin for broad-spectrum antibiotic coverage, particularly against streptococci.
- Enterococci exhibit resistance to streptomycin and gentamicin, posing a challenge to current preservation methods.
Observation:
- Enterococcus faecium was isolated from donor limbus and corneal rim cultures.
- The organism was detected before corneal excision and after 5 days of preservation in OptiSol-GS.
- The isolated Enterococcus faecium demonstrated resistance to both gentamicin and streptomycin.
Findings:
- Donor corneas can harbor antibiotic-resistant Enterococcus faecium despite preservation in OptiSol-GS.
- Standard antibiotic combinations in corneal storage media may not effectively eliminate all potential bacterial contaminants.
- Persistent bacterial viability underscores the limitations of current donor tissue decontamination protocols.
Implications:
- Increased awareness is needed regarding the potential for viable streptococcal and enterococcal contaminants in donor corneas preserved in OptiSol-GS.
- This case highlights the need for enhanced screening or alternative preservation strategies to mitigate endophthalmitis risk.
- Further research into novel antimicrobial agents or preservation techniques is warranted to improve donor cornea safety in transplantation.