Use of Topical Colistin in Multiple Drug-Resistant Pseudomonas aeruginosa Bacterial Keratitis

PURPOSE: The aim of this study was to report the utility of topical colistin in multi-drug resistant Pseudomonas aeruginosa bacterial keratitis. METHODS: Retrospective interventional case series included 8 patients with culture-proven multi-drug resistant P. aeruginosa (MDR-PA) bacterial keratitis who presented from June 2011 to January 2012 and were treated with colistin 0.19% as monodrug therapy. Clinical/microbiological data were collected from medical records. All patients underwent microbiological corneal scraping. Intensive half-hourly therapy with broad-spectrum antibiotics was changed to colistin 0.19% when antibiotic sensitivity reports were available. The outcome was a "complete success" if resolution of infection occurred with scar formation without any subsequent recurrence up to 2 weeks and "partial success" if it also required a cyanacrylate glue application. The outcome was a "failure" if the patient required a therapeutic graft or if the infection could not be controlled and the eye needed evisceration. RESULTS: The mean age was 45 ± 16 years; the M:F ratio was 1:1. Seven patients had a history of ocular surgery. The mean size of the infiltrate was 15.41 ± 22.2 mm and was full thickness in 5 patients. Success was achieved in 7 out of 8 patients, and the infiltrate gradually decreased with resolution of infection in a mean duration of 30.5 ± 16 days. Complete and partial success were noted in 4 and 3 patients, respectively. The final visual acuity was 20/60 or better in 4 patients. One patient required a sclerocorneal patch graft. No complications of topical colistin were noticed. CONCLUSIONS: The early use of topical colistin 0.19% was found to be a safe and effective alternative in the management of multi-drug resistant P. aeruginosa bacterial keratitis.