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A. R. Caballero, C. L. Balzli, C. C. McComrick, B. Huang, L. Wigington, A. Tang, R. J. O'Callaghan; Fluoroquinolone Therapy for Experimental LASIK-Associated Staphylococcus Keratitis. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2675.
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To develop, in the rabbit, a unique model of post-LASIK keratitis mediated by Staphylococcus aureus and to determine the effectiveness of ocular fluoroquinolone antibiotics.
A corneal flap was created in the rabbit corneas (n = 6 eyes per group) using a microkeratome (Bausch and Lomb Hansatome Excellus). S. aureus strain 91169 (500 CFU, 5 µl), an ulcerative keratitis isolate, was administered under the flap. For prophylactic therapy, a single topical drop of moxifloxacin (0.5%, Vigamox) or gatifloxacin (0.3%, Zymar) was applied at 5 hours before infection and the number of bacteria per cornea was determined 5 hours postinfection (PI). For therapy of active infection, eyes were treated with a single topical drop of antibiotic every hour from 4 to 9 hours PI and the bacterial load determined at 10 hours PI. Corneal homogenates were cultured quantitatively in triplicate; results are expressed as the log CFU ± SEM.
Bacteria inoculated under the corneal flap grew logarithmically for 10 hours reaching 6.20 ± 0.006 CFU per cornea. Conjunctival chemosis and injection and corneal infiltration and epithelial erosion were observed after 12 hours postinfection. Eyes treated prophylactically with moxifloxacin or gatifloxacin contained 4.76 ± 0.04 or 4.82 ± 0.052 CFU per cornea, respectively, and were significantly lower than the untreated control (P = 0.002 or P = 0.013, respectively). For therapy of infected eyes, eyes treated with moxifloxacin or gatifloxacin contained 1.02 ± 0.145 or 1.18 ± 0.047, respectively, and were significantly lower than the untreated control (P < 0.0001 or P < 0.0001, respectively).
Infection of the rabbit corneal flap provided a reliable model of keratitis mimicking that following LASIK surgery. Moxifloxacin therapy, relative to gatifloxacin therapy, yielded similar, but numerically superior, bacterial killing following either prophylactic therapy or therapy of active infection.
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