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Riley Bylund, Clinton Ellingson, Douglas Katz; ESwab Verse Scalpel Blade Scraping for the Corneal Ulcer. Invest. Ophthalmol. Vis. Sci. 2018;59(9):3672.
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© ARVO (1962-2015); The Authors (2016-present)
Residents at the University of Kentucky see on average 34 corneal ulcers each year, many referred by rural providers. Ideally, empiric antibiotic drops are initiated after culturing, however, culturing corneal ulcers requires resources and experience often absent in rural settings. When delaying empiric antibiotics, the referring provider must consider the consequences of uncertain follow up. The purpose of this prospective study was to compare the non-inferiority of a new, simple, accessible collection method (ESwab; Copan Diagnostics, Inc) to the standard of care at the University of Kentucky: culture by #15 Parker scalpel blade. The primary outcome measured was concordance of culture growth between samples collected with the scalpel blade and the ESwab. Secondary outcomes measured were consistency between experienced and inexperienced providers, short versus prolonged ESwab incubation time, and the effect of prior antibiotic administration on culturing results.
Consenting patients with suspected corneal keratitis were enrolled. Each received the standard individual corneal scrapings with a #15 Parker blade for gram stain, KOH slide, blood, chocolate, MacConkey and Sabouraud agars. The ESwab was inoculated by gently touching it to the corneal ulcer after the second scraping. All collections were sent for culturing. After 4 and 24 hr incubation periods the same slides and agar plates were inoculated with the ESwab by the lab.
38 samples from consenting patients were collected. The concordance between cultures from the scrapings and the ESwab was 97.3% (37/38) at 4hr incubation interval. Of the antibiotic naive samples, concordance was 92.8% (13/14) at 4hr incubation interval. At 24 hours the ESwab was more likely to have growth; 11 samples yielding a positive culture when scrapings were negative. There was 100% (19/19) concordance between the scrapings and 24hr cultures when the scrapings were positive. There appeared to be no difference in culture rates between experienced and inexperienced providers.
The ESwab collection method is a simple, accessible, cost effective alternative to corneal scraping with a #15 Parker blade. This study demonstrates corneal culturing by ESwab is non-inferior to scalpel blade. This collection method provides an effective culturing option to eye physicians without a proximal microbiology lab and could increase the number of pathogen focused antibiotic treatment plans.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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