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Effectiveness of Mupirocin and Polymyxin B in Experimental Staphylococcus aureus, Pseudomonas aeruginosa, and Serratia marcescens Keratitis

Moreau, Judy M. M.S.; Conerly, Lisa L. M.S.; Hume, Emma B.H. Ph.D.; Dajcs, Joseph J. B.S.; Girgis, Dalia O. B.S.; Cannon, Bennetta M. M.S.; Thibodeaux, Brett A. B.S.; Stroman, David W. Ph.D.; O'Callaghan, Richard J. Ph.D.

Cornea:
Basic Investigations
Abstract

Purpose. The purpose of this study was to determine the effectiveness of mupirocin and polymyxin B, alone and in combination, in vitro and in vivo using rabbit models of Staphylococcus aureus, Pseudomonas aeruginosa, and Serratia marcescens keratitis.

Methods. Rabbit eyes were intrastromally injected with 1,000 colony-forming units (CFUs) of P. aeruginosa or S. marcescens or 100 CFUs of S. aureus. Rabbits were then treated with 2.7 mg/mL mupirocin, 10,000 U/mL polymyxin B, a mupirocin:polymyxin B combination, or 0.3% ciprofloxacin. Vehicle and untreated controls were also included. Treatment schedules depended on the strain injected. The number of CFUs was determined for all eyes after treatment.

Results. The mupirocin:polymyxin B combination was effective for all three genera both in vitro and in vivo. For S. aureus keratitis, the mupirocin:polymyxin B combination was more effective than either drug alone and significantly reduced the log number of bacteria in the cornea by more than 3 logs compared with the vehicle or untreated controls (p ≤ 0.0016). For P. aeruginosa, the mupirocin:polymyxin B combination treatment significantly reduced the number of CFUs per cornea relative to the individual drugs, vehicle, or untreated controls (p ≤ 0.016). For S. marcescens, the mupirocin:polymyxin B combination therapy significantly reduced the number of bacteria in rabbit corneas relative to the individual drugs, vehicle, or untreated groups (p ≤ 0.0001). Therapy with the mupirocin:polymyxin B combination was equivalent to ciprofloxacin therapy (p = 0.80).

Conclusion. The mupirocin:polymyxin B combination was effective in treating experimental S. aureus, P. aeruginosa, and S. marcescens keratitis.

Author Information

From the Department of Microbiology, Immunology, and Parasitology (J.M.M., L.L.C. E.B.H.H., J.J.D., D.O.G., B.M.C., B.A.T., R.J.O.), LSU Health Sciences Center, New Orleans, LA; Alcon Research Limited (D.W.S.), Fort Worth, TX; and the Department of Ophthalmology (R.J.O.), LSU Eye Center, New Orleans, Louisiana, U.S.A.

Submitted January 17, 2002.

Revision received July 2, 2002.

Accepted July 2, 2002.

Support: NEI grant EY10974, NEI core grant EY02377, and a donation from Alcon Research Limited to the LSU Medical Center Foundation.

Address correspondence and reprint requests to Richard O'Callaghan, Ph.D., Department of Microbiology, Immunology and Parasitology, LSU Health Sciences Center, 1901 Perdido Street, New Orleans, LA 70112, U.S.A. E-mail: rocall@lsuhsc.edu

© 2002 Lippincott Williams & Wilkins, Inc.