Failures in diagnosis and monitoring plague management of bacterial keratitis

Establishing the correct diagnosis and modifying therapy appropriately based on response are fundamental in the successful management of bacterial keratitis, said Richard L. Abbott, MD, at the World Congress of Ophthalmology.

"Left untreated, microbial keratitis leads to progressive tissue destruction with potential corneal perforation and extension to adjacent structures. Determining etiology is critical for effective management," said Dr. Abbott, the Thomas W. Boyden Professor of Ophthalmology, Beckman Vision Center, University of California at San Francisco.

In their clinical evaluation, ophthalmologists need to recognize there are many conditions that are masqueraders of bacterial keratitis. Therefore, obtaining a culture with use of proper sampling and plating technique is critical in all suspect cases.

Once treatment is initiated, patients need to be closely observed to determine if the infection is responding, worsening, or if the changing clinical picture is indicative of medication-related toxicity. Dr. Abbott recommended creating a carefully drawn diagram in the chart that includes information about: 1) the depth and density of the infiltration, 2) thinning, 3) the presence and density of white blood cells around the infiltrate, and 4) the size and density of hypopyon. Those features should then be followed in the evaluation of the treatment response.

In the current era, treatment is usually initiated with a fourth-generation fluoroquinolone administered in an intensive regimen for the first several days. Once there is evidence of therapeutic response, the treatment should be tapered to avoid toxicity, but fluoroquinolone administration frequency should never be reduced to below four times a day. When fluoroquinolone discontinuation is deemed appropriate, clinicians who wish to maintain antibiotic coverage may prescribe bacitracin, as that agent offers broad-spectrum activity and is well-tolerated, said Dr. Abbott.