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GJ Ben Simon, M Cahane, O Goller, L Diamantstein-Weiss, A Grinbaum, I Barequet, E Rubinstein, I Avni; Corneal Tissue Levels of Topically Applied Vancomycin . Invest. Ophthalmol. Vis. Sci. 2002;43(13):47.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To evaluate vancomycin penetration into human corneal stromal tissue in patients treated with topical vancomycin eyedrops before penetrating keratoplasty (PKP). Methods: Twenty-four patients who underwent penetrating keratoplasty were divided into 2 groups, 7 patients with keratoconus (group 1) and 17 patients with corneal scar or corneal decompensation (group 2). All patients received topical eyedrops of vancomycin (concentration: 33mg/ml) 10, 3, 2, 1 hours and 15 minutes before the operation. The control group consisted of 4 patients (2 males, 2 females, mean age 57.25+/-17.46, range 40-78) who did not receive any antibiotic in any form before the operation. The conjunctival fornices were thoroughly irrigated with saline and the epithelial layer was removed prior to trephination of the corneal buttons. Corneal vancomycin level was assessed by bioassay. Protein content within the solution was measured. Bacterial cultures were obtained from the conjunctival cul de-sac before and after treatment with vancomycin. Results: Mean vancomycin corneal stromal tissue concentration was 46.7 (±20.17 (mcg/gr tissue). This value exceeds 4-20 fold the MIC of vancomycin towards Staphylococcus aureus (2-10 mcg/ml). There was no statistical difference between group 1- 40.16±10.05 mcg/gr and group 2 - 49.40±22.82 mcg/gr, p=0.183 (Student's t test). Average vancomycin concentration to protein content was 1.25±0.58 mcg/mg protein. Vancomycin stromal concentration was statistically significantly greater in group 2 (1.36±0.65 mcg/gr) than in group 1 (0.9±80.19 mg/gr), p=0.036 (Student's t test). The level of vancomycin in the control group was not detectable by bioassay (marked as 0). Conclusion: Vancomycin reached high corneal tissue levels that significantly exceeded the MIC90 (2-10 mg/L) for most key Gram-positive corneal pathogens. There was no difference in corneal vancomycin concentration between group 1 (keratoconus) and group 2 (other medical indications for PKP). Vancomycin concentraion by protein content was significantly higher in group 2 (non-keratoconus). As keratoconus corneas usually have an intact epithelium, indeed lower vancomycin penetration is expected than with cases such as failed graft, leucoma cornea or corneal decompensation
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