2003 OMIG, Abstract 22

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Effectiveness of Fluoroquinolone Antibiotics for Experimental Mycobacterium chelonae Keratitis
A.R. Caballero, B.A. Thibodeaux, J.J. Dajcs, M.E. Marquart, K.H. Johnston, J.T. Bush and R.J. O’Callaghan. LSU Health Sciences Center in New Orleans.

Purpose: To determine the effectiveness of a new fluoroquinolone for treating M. chelonae using a rabbit model of keratitis.
Methods: An ATCC strain (19235) or a clinical isolate (M. chelonae GS) were grown in Middlebrook medium and injected intrastromally into rabbit corneas (104 CFU). Dexamethasone phosphate was injected subconjunctivally (2 mg/eye). Antibiotics tested were 0.3% ciprofloxacin (Ciloxan) and 0.5% moxifloxacin (Vigamox). Eyes were treated topically with one drop of antibiotic applied hourly for 10 hours on day 3 post-infection (PI) or with one drop applied every two hours for 10 hours on days 1, 2 and 3 PI. Corneas were harvested and cultured one hour after the last topical drop.
Results: Untreated controls of strain 19235 maintained 4 logs CFU/ cornea for 3 days then underwent a steady decline to less than 1 log CFU by day 12. Clinical strain GS increased in numbers in the cornea and grew to 6 logs CFU/cornea by day 3. Treatment of strain 19235 on day 3 PI resulted in 0.3 and 1.33 log reductions in CFU/cornea for ciprofloxacin and moxifloxacin, respectively, relative to the untreated control (4.17 logs). Treatment of eyes infected with strain GS on days 1 to 3 with moxifloxacin resulted in 5.76 log reduction in CFU/cornea relative to the untreated control (6.24 logs). Moxifloxacin significantly reduced the numbers of Mycobacteria in the cornea for strains 19235 and GS (P<0.0001).
Conclusion: Moxifloxacin demonstrated significant effectiveness for treating experimental mycobacterial keratitis. Supported by LSUHSC Foundation (thanks to a donation from Alcon Laboratories, Inc.) and NEI grant EY10974.

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