Microbiological Screening of Hypothermic Preserved Donor Corneas in Keratoplasty

Purpose: To determine the prevalence, risk factors and microbial profiles of donor corneal contamination and its association with postoperative infection. Materials and Methods: 1348 hypothermic preserved donor corneas were screened during keratoplasty to assess the impacts of donor age, gender, cause of death and corneal preservation time on the contamination risk. The microbial spectrum and antibiotic sensitivity of causative microorganisms and the prognostic role of corneoscleral rim cultures were analyzed. Results: 111 donor corneas (8.2%) had positive microbial cultures, with 84 contaminated by bacteria, 25 by fungi and 2 by both. Acinetobacter baumannii complex (19.8%) and Candida spp. (9.0%) were the most commonly isolated bacteria and fungi, respectively. Two patients (1.8%) who received contaminated corneal buttons developed postoperative infections. Death due to cardiac disease led to more corneal contaminations than death due to brain disease (odds ratio (OR) = 2.59, P = .009). Longer preservation time was associated with a trend toward increasing contamination rate (from 8.3% to 15.0%). Moreover, fungal-contaminated corneas were preserved longer than bacterial-contaminated corneas (6.6 ± 4.5 versus 10.2 ± 5.4 days, P = .001). Corneas from donors who died from cardiac diseases and trauma showed the highest prevalence of bacterial (10.9%) and fungal (2.6%) contamination, respectively. Antibiotic sensitivity testing revealed that the third-generation fluoroquinolone levofloxacin had high rates of susceptibility to both gram-positive (G+) (60.0%) and gram-negative (G-) (44.6%) bacteria. Conclusions: The causes of donor corneal contamination are multifactorial. The antibiotic resistance rate of contaminating microbes seems to be increasing. Whether antibiotic usage in storage medium and postoperative prophylaxis should be updated accordingly warrants further investigation.