Evolution ? Sharma S, Kunimoto

Evolution ?

Sharma S, Kunimoto DY, Garg P, and Rao GN. "Trends in antibiotic resistance of corneal pathogens: Part I. An analysis of commonly used ocular antibiotics." Indian J. Ophthalmol [serial online] 1999

The authors of this study examine bacterial keratitis as the primary pathogen and analyze it root causes as well as the effects of antibiotics that are commonly in use in the current treatment of the disease. They also focus on two age groups that are particularly susceptible to this disease, the elderly population and the pediatric cohort. Both are sensitive to the debilitating effects of this pathogen. The authors hope to refine and improve the current diagnostic procedure and treatment of the disease.

Part I of this series is addressed mainly to community-based ophthalmologists who do not have access to extensive microbiology facilities, and discusses the in-vitro effectiveness of commonly used ocular antibiotics describing their coverage of bacterial species, in the hope that this information will aid in the decision-making of empiric initial treatment. (Sharma, Kunimoto, Garg, & Rao)

Bacterial keratitis is a sight-threatening degenerative disease. One particular dangerous feature of this pathogen is its rapid progression. Complete corneal destruction may occur in under forty-eight hours with some of the more virulent strains of the bacteria. Corneal ulceration, stromal abscess formation, surrounding corneal edema, and anterior segment inflammation are primary characteristic of this infection. (Murillo-Lopez)

According to the authors the main purpose of this study was "…to analyze commonly used ocular antibiotics and determine their in-vitro efficacies against bacterial keratitis pathogens." (Sharma, Kunimoto, Garg, & Rao) the method used was first a review of the microbiology records held at LV Prasad Eye Institute in Hyderabad, India. In these records they identified 1,633 bacterial keratitis isolates and using standard methods they obtained corneal scrapings which they cultivated in culture dishes to produce strains of the bacteria. They presented the following results after testing seven antibiotics in table 2 of their article, table 1 for this review.

Table 1: (Sharma, Kunimoto, Garg, & Rao)

For ophthalmologists without access to microbiology facilities and treating patients on an empirical basis, [Table - 2] provides information which may guide the clinician in making a decision when a change in antibiotic is necessary due to an unsatisfactory clinical response to initial antibiotic therapy. (Sharma, Kunimoto, Garg, & Rao)

However, the authors' results propose that no one antibiotic they had tested would be "appropriate as initial empiric monotherapy for bacterial keratitis, either due to a gap in coverage or unacceptably low coverage." (Sharma, Kunimoto, Garg, & Rao) They believe that he information they are providing will allow the clinician to have a more expansive approach in treating bacterial keratitis and in deciding which secondary antibiotic to use.

The goal of initial antibiotic therapy for bacterial keratitis is the proper selection of a drug which has coverage for the aetiopathogen. Microscopic evaluation of corneal smears can provide insight into the identity of the pathogen, but when smear examination is uninformative the principle of managing bacterial keratitis has been to use antibiotics which have coverage that is sufficiently broad and effective to treat the leading corneal pathogens. (Sharma, Kunimoto, Garg, & Rao)

The main thrust for their interest in this study was to assist the clinician who is in less that ideal setting when faced with treating bacterial keratitis. As mentioned previously the virulent nature of this disease necessitates immediate treatment but the proper facilities are not always present for the clinician to extract corneal scrapings for analysis. Therefore they have provided information that will help this clinician to use secondary antibiotic with a certain degree of judgment when initial antibiotic treatment is unsuccessful. This should provide assistance in all areas of treatment for this disease. Furthermore, by increasing the information available regarding success rate of various antibiotic therapies, the authors hope to reduce the time necessary in stopping the further deterioration of the patient's eyesight.