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Contamination of donor cornea by gentamicin-resistant organisms
Abstract:
Cultures of the donor corneoscleral rims in 70 consecutive penetrating keratoplasties showed microbial contamination in 14 cases. All positive cultures were tested by standard microdilution broth method for sensitivities to gentamicin, an antibiotic routinely used in McCarey-Kaufman transport medium. Seven of 15 organisms demonstrated resistance to gentamicin at concentrations above 100 micrograms/ml. These results indicated the selection of more antibiotic-resistant microorganisms in antibiotic-supplemented medium and the need for appropriate antibiotic prophylaxis at the time of surgery.
Insights
Microbial contamination occurred in 14% of donor corneas. Many organisms showed gentamicin resistance, suggesting antibiotic-supplemented media may select for resistant microbes, highlighting the need for surgical antibiotic prophylaxis.
Area of Science:
- Ophthalmology
- Microbiology
- Transplantation Science
Background:
- Donor corneoscleral rims are crucial for penetrating keratoplasty.
- Microbial contamination of donor tissue can lead to graft failure.
- McCarey-Kaufman medium is commonly used for corneal preservation.
Purpose of the Study:
- To assess microbial contamination rates in donor corneas.
- To determine the antibiotic resistance patterns of contaminating organisms.
- To evaluate the efficacy of gentamicin in transport media.
Main Methods:
- Cultures of 70 donor corneoscleral rims were analyzed.
- Positive cultures were tested for microbial contamination.
- Antibiotic sensitivity testing using microdilution broth method was performed for gentamicin.
Main Results:
- Microbial contamination was found in 14 out of 70 cases (20%).
- Seven of the 15 identified organisms exhibited resistance to gentamicin.
- Resistance was observed at concentrations exceeding 100 micrograms/ml.
Conclusions:
- Antibiotic-supplemented transport media may inadvertently select for antibiotic-resistant microorganisms.
- The findings underscore the importance of appropriate antibiotic prophylaxis during penetrating keratoplasty surgery.
- Further research into optimal antibiotic strategies for corneal preservation is warranted.