Changes of Contamination Rate and Microorganism Evaluation in Organ-Cultured Human Corneas: A 14-Year Review From a French Regional Eye Bank

Purpose: This study aimed to assess how the contamination rate of organ-cultured corneas has evolved and to analyze the evolution of microorganisms involved. Methods: Data from the Besancon eye bank were reviewed over 14 years (2005-2018). The changes in the contamination rate and the contaminant species found during the organ culture storage were analyzed. Microbiological tests were performed twice on the storage media-at day 5 and before the deswelling phase. Results: Among the 17,979 donor corneas collected, 1240 corneas were microbiological-test positive. The average annual contamination rate was 6.8% (range: 5.2%-8.9%). Seventy-five percent of contaminations were bacterial. The most frequently found bacterium was Staphylococcus spp. (31.3%), followed by non-Enterobacteriaceae Gram-negative Bacilli (GNB) (27.3%), with most Sphingomonas spp. and Pseudomonas spp. Fungal contamination (21.9%) was dominated by Candida (82.7%). Seventy-seven types of microorganisms were identified. The Staphylococcus rate tended to decrease, whereas non-Enterobacteriaceae GNB rate has increased in the past few years to reach 46% of bacteria. Most of the contaminations were detected in the early phase of organ culture at day 5 (89.2%). The second microbiological test found 44.8% of fungal contaminations (predominantly Candida spp.). Conclusions: The annual contamination rate was stable and remains low, but the types of contaminating microorganisms varied from year to year. Staphylococcus spp. and non-Enterobacteriaceae GNB accounted for a significant proportion of the contaminations. We found a significant proportion of contamination, especially fungal, at the late phase of storage. Reassessing the antibiotics and antifungals in the storage medium may be useful to limit corneal disposal.