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A. Tang, A. R. Caballero, C. C. McCormick, C. L. Balzli, R. J. O'Callaghan; A New Topical Model of Staphylococcus aureus Keratitis in a Scarified Rabbit Eye. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2397.
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© ARVO (1962-2015); The Authors (2016-present)
Currently there is no rabbit model of Staphylococcus keratitis that mimics the human infection in which bacteria in the tear film infect the cornea. Such a model would be useful for studies of antibiotic effectiveness and mechanisms of pathogenicity. The present study was designed to create a topical model of keratitis in the rabbit.
Rabbit corneas were scarified with a 30 gauge needle and 5×105 colony-forming units (CFU) of S. aureus strain UMCR1 was topically applied. At 5, 10, 15, and 25 hours postinfection (PI), inoculated eyes underwent slit lamp examination (SLE) as a measure of pathological changes and quantitative culturing was performed to determine the number of CFU (± SEM) present. Pathological changes were also analyzed by corneal histopathology and determination of the log number (± SEM) of polymorphonuclear leukocytes (PMNs) per cornea using the myeloperoxidase (MPO) assay.
Inoculated rabbit corneas developed severe keratitis within 25 hours PI. Bacterial numbers in infected corneas increased steadily from 5 hours PI (4.35 ± 0.52 log CFU) to 25 hours PI (6.30 ± 0.24 log CFU). The SLE scores also increased steadily from 5 hours PI (0.94 ± 0.04) to 25 hours PI (16.83 ± 0.55). Histopathology demonstrated the presence of edema and PMNs in the infected cornea. MPO assays quantified the infiltrating PMNs at 15 hours PI (5.93 ± 0.08 log PMN) and at 25 hours PI (6.05 ± 0.10 log PMN).
A new rabbit S. aureus keratitis model based on the inoculation of bacteria into the rabbit tear film was established. The model is reproducible and appears well suited for chemotherapy and pathogenesis studies.
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