Evaluation of the decontamination of donor cornea

Abstract: The aim of the study was to evaluate two strategies for decontamination of donor cornea.
Thirty donor corneas were procured by Monza Eye Bank. Ten corneas were transferred into decontamination medium “A” at 31°C for 28 days. Twenty corneas were decontaminated with medium “B” at 22°C, overnight, and subsequently stored either in Eusol-C (AL.CHI.MI.A. S.r.l) at 4°C for 10 days or in Tissue-C (AL.CHI.MI.A. S.r.l) at 31°C for 20 days. The decontamination phase was skipped for control tissues, which were stored either in Eusol-C or in Tissue-C. Microbiological contamination, endothelial cell density (ECD), endothelial morphology and mortality were monitored pre-processing, 24h post-decontamination and post-processing. For microbiological analyses, both Bactec system (BD) and sterility test according to European Pharmacopeia after antibiotic residues removal were used. Presence of antibiotic residues was monitored by HPLC.
Almost all tissues were initially contaminated with bacterial and/or fungal species. All post-decontamination corneas showed negative microbiological analyses. In both control and post-decontamination samples, HPLC analysis showed presence of antibiotics prior to microbiological analyses. Corneas stored in decontamination solution “A” did not show variation of ECD or endothelial morphology up to 14 days. After 21 days, endothelial morphology was severely altered as compared to control tissues. Overnight decontamination with medium “B” resulted in similar ECD, endothelial morphology and mortality rate as compared to control tissues.
Overnight decontamination, before tissue conservation, allowed to eliminate all contaminants from donor corneas without tissue alteration. Presence of antibiotic residues could interfere with microbial growth. Therefore their accurate removal is necessary prior to microbiological testing.