The prevalence and risk factors for donor corneal button contamination and its association with ocular infection after transplantation

BACKGROUND: One of the most serious complications of corneal transplantation is postoperative ocular infection, which may result in loss of the eye. Contamination of the donor corneal button before transplantation may result in such complication. PURPOSE: To evaluate the prevalence of donor corneal button contamination, the spectrum of the contaminating microorganisms, and their sensitivity to antimicrobial agents. To investigate the risk factors for contamination of the donor corneal buttons and the effect of corneal button contamination on the prevalence of ocular infection in corneal transplanted patients. SETTING: Tertiary referral medical center. MATERIALS AND METHODS: Four hundred sixty-nine corneal transplantations were included in the study. Microbial cultures from the corneoscleral rims of the donor corneal buttons were obtained for isolation of bacteria and fungi and for their sensitivity to antimicrobial agents. Ocular microbial cultures were also obtained from corneal transplanted patients with clinical signs of ocular infection (ie, corneal scrapes from corneal ulcers and vitreous tap from eyes with endophthalmitis). RESULTS: Seventy-nine donor corneal buttons (16.8%) had positive bacterial cultures, and none had positive fungal culture. Staphylococci (63.7%) and streptococci (11.3%) were the most common isolated bacteria. Sensitivity to vancomycin, amikacin, and gentamicin was found in 71.3%, 28.5%, and 22.3% of all isolated bacteria, respectively. Malignancy and cardiac diseases as causes of donor death were associated with donor button contamination (P = 0.043 and P = 0.011, respectively), and septicemia was a marginally significant risk factor (P = 0.059). Age and gender of the donor, duration from death to corneal button harvesting, and time from harvesting to transplantation were not found significant risk factors for contamination. Six of the corneal transplanted patients (1.27%) had infected corneal graft ulcer, and 1 (0.22%) had endophthalmitis. The infected corneal ulcer appeared between 3 and 14 days (average 5 days), and endophthalmitis was disclosed 8 months after transplantation. Two (33%) of the 6 patients with corneal ulcer had the same species as the donor corneal rim. Postoperative ocular infection occurred in 2 (2.5%) patients out of 79 who received contaminated corneal buttons compared with 5 (1.3%) out of 390 patients who received sterile corneal buttons (P = 0.335). CONCLUSIONS: Postkeratoplasty infection of the recipient eye is infrequent despite relatively high prevalence of microbial contamination of the corneal buttons, suggesting that other risk factors for postoperative ocular infection are involved.