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Light-Blocking Infiltrates in Donor Corneas Preserved in Optisol: Infection or Inflammation?
Ellen L. Heck, MT, MA, Alison Dingrando, CEBT, Jerry Y. Niederkorn, PhD, H. Dwight Cavanagh, M.D., PhD
Microbial colonization, nosocomial infections, ventilator support
This prospective study examined corneal infiltrates in donor corneas as compared to previously reported isolates to determine if the changing patterns in nosocomial infections, Acinetobacter and Clostridium difficile reported in a recent government study was also occurring in the corneal donor population. Corneas from 50 donors, in which tissue was subjected to ocular surface disinfection by standard protocols and found on slit lamp examination to have corneal infiltrates, were included for study. Infiltrates were identified by technicians during slit lamp examination after tissue had been placed in solution containing antibiotics. Fifty of these corneas, in which bilateral infiltrates were present, were submitted for bacteria and fungi culture and histological examination. Of the 50 corneas, 13 (26%) were culture-positive, predominantly Candida albicans and Staphylococcus aureus, with no shift in the microbial pathogens from previous studies. There were no isolates of Acinetobacter. In 21 corneas in both culture and histological examination, organisms were present extracellularly and intracellularly in corneal epithelial cells and infiltrate macrophages. Since many corneal donors are from hospital populations, individuals having undergone mechanical ventilation, it is important to know there has been no shift in microbial pathogen profiles suggested by CDC report for Acinetobacter/Clostridium difficile. Importantly, ventilation intervals do not appear predictive for the presence of invasive pathogens in corneas with light blocking infiltrates as had previously been hypothesized. Nevertheless, continuing awareness and monitoring for shifts in hospital microbial infections represent important safeguards in preventing donor related infections as corneal infiltrates cannot be attributed to a singular circumstance; i.e. ventilation.