Trends in antibiotic resistance of corneal pathogens: Part I. An analysis of commonly used ocular antibiotics

Abstract

Purpose: To analyse commonly used ocular antibiotics and determine their in-vitro efficacies against bacterial keratitis pathogens. Methods: A retrospective review of microbiology records at the LV Prasad Eye Institute in Hyderabad, India identified 1,633 bacterial keratitis isolates. Antibiotic susceptibility of corneal isolates was determined for various ocular antibiotics using the Kirby-Bauer disc-diffusion method. Results: Cefazolin had coverage against 1,296 (83.0%) of 1,562 isolates tested; chloramphenicol against 1,136 (71.7%) of 1,585 isolates; ciprofloxacin against 1,080 (69.3%) of 1,558 isolates; gentamicin against 1,106 (70.6%) of 1,567 isolates; norfloxacin against 1,057 (67.7%) of 1,561 isolates; vancomycin against 463 (84.3%) of 549 isolates; and framycetin against 105 (36.2%) of 290 isolates. Also included is a breakdown by species, and sensitivity profiles for resistant isolates.Conclusion: This study provides information on the efficacies of ocular antibiotics commonly used against bacterial keratitis pathogens. It also examines the antibiotic susceptibility profiles for corneal pathogens that are resistant to an ocular antibiotic but sensitive to other selected antibiotics. It is hoped that this information will aid in the decision-making of empiric initial treatment of bacterial keratitis.