Trends in antibiotic resistance of corneal pathogens: Part II. An analysis of leading bacterial keratitis isolates

Abstract

Purpose: To analyse leading bacterial keratitis pathogens for in-vitro susceptiblity to commonly used ocular antibiotics and to determine trends in antibiotic susceptibility for these pathogens. Methods: A retrospective review of microbiology records from 1991-1997 at the LV Prasad Eye Institute, Hyderabad, India identified the five leading bacterial keratitis pathogens.. Antibiotic susceptibility of corneal isolates was determined for various ocular antibiotics using the Kirby-Bauer disc-diffusion method. Results: Linear regression analyses were performed. Statistically significant trends included a 3.56% increase per year in the percentage of Staphylococcus epidermidis isolates susceptible to chloramphenicol (p = 0.032) [-6.61 - -0.51, 95% CI]; a 9.93% decrease per year in the percentage of Corynebacterium species isolates susceptible to ciprofloxacin (p = 0.050) [0 -19.86, 95% CI]; a 0.69% increase per year in the percentage of Staphylococcus aureus isolates susceptible to gentamicin (p = 0.012) [-11.35 - -2.49, 95% CI]; and a 5.53% increase per year in the percentage of Staphylococcus aureus isolates susceptible to norfloxacin (p = 0.040) [-10.66 - -0.40, 95% CI]. A trend of borderline significance included a 3.77% decrease per year in the percentage of Pseudomonas aeruginosa isolates susceptible to ciprofloxacin (p=0.064) [-0.34 - 7.89]. Conclusion: This study provides information on the trends in antibiotic susceptibility for the leading bacterial keratitis pathogens. It is hoped that this study will provide a rational approach for initial therapy, taking into account changing trends in antibiotic susceptibility.