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André Philipp Klamann, Christina Hildebrandt, Anja Katharina Gruenert, Gerd Geerling, Thomas Armin Fuchsluger; Conjunctival swabs of cornea donors and medium contamination. Invest. Ophthalmol. Vis. Sci. 2014;55(13):5455.
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© ARVO (1962-2015); The Authors (2016-present)
Following recent regulations of the German national authority, every cornea donor eye has to undergo microbiological examination twice using a corneal swab before corneal excision or enucleation. Aim of this study is to analyze detected pathogens, the relation to the donor retrieval location and the incidence of related contaminations of the storage medium.
Two conjunctiva swabs from each of the 326 eyes were taken prior to corneoscleral excision of the donor tissue. The swabs were examined for bacterial and fungal pathogens by the Institute for Medical Microbiology and Hospital Hygiene at Dusseldorf University Hospital. In addition, corneal culture medium was analyzed for pathogens at each medium change (8 day interval).
28.22% of the donor eyes were positive for microbial pathogens (n=92). The predominant pathogens was staphaphylococcus epidermidis (40.2%). Other pathogens included staph. aureus (13.0%), e. coli (11.9%), coagulase-negative staphylococcus (10.9%), enterococcus (6.5%), candida albicans (4.5%), pseudomonas aeruginosa (3.5 %) (other germs = 17.5%). Relative to locations of cornea collection, swabs resulted in positive results in 40.9% of donor eyes located at Dusseldorf Central Cemetery, Institute of Anatomy (38.9%), external clinics (28.8%), Institute of Pathology (22.4% ) and the Institute of Forensic Medicine (21.9%). Interestingly and importantly, this resulted in only 7,7% of positive medium contaminations (n=25). 28% c. albicans, 24% enterococcus faecium, 12% of e. coli, 12% of staph. haemolyticus, 8% candida parapsilosis, 8% proteus mirabilis, 4% candida glabrata, 4% candida tropicalis, 4% of coagulase-negative staphylococcus and 4% pseudomonas aeruginosa. Surprisingly, the germ causing positive medium contamination was in mere 7% equivalent to the germ detected on the ocular surface of the respective donor cornea.
Our data demonstrate that a positive conjunctival swab is not a strong indicator for contamination of cornea culture medium. There is a very low probability positive conjunctival swabs result in medium contamination. Furthermore, in corneal collection within the campus (Depts. of Pathology or Forensic Medicine) positive swabs are significantly less positive in comparison to external institutions (Central Cemetery, Forensic Medicine). A critical discussion is necessary about the validity of the conjunctival swabs as a prognostic parameter for a medium contamination.
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