Ocular infections--a rational approach to antibiotic therapy.

Background: Isolation of common pathogens involved in ocular infection and their in-vitro susceptibility to commonly used ocular antibiotics, as well as the trends in antibiotic resistance developed by these pathogens were investigated. Material/Methods: All patients with suspected bacterial ocular infections presenting between march 2010 and feb 2011 were examined under slit lamp microscope and samples were collected by using aseptic techniques. All samples were processed for direct microscopy, culture and identification by standard methods. Susceptibility testing was done by Kirby-Bauer method as per CLSI guideline. Results: Out of 116 patients with ocular infections 130 samples were collected, from which 38 different organisms were isolated. Gram-positive cocci 21 (55%), gram-negative cocco-bacilli 5(31%) and gram-negative bacilli 12 (32%) were isolated. Coagulase negative Staphylococci (37%) and Pseudomonas species (21%) were the most commonly-isolated. Gatifloxacin has highest efficacy (89%) against all isolates. Majority of gram positive cocci were susceptible to vancomycin, gatifloxacin, cefazolin, gram negative cocco-bacilli to amikacin, tobramycin, fluoroquinolone and gram negative bacilli to gatifloxacin. Conclusion: Majority of ocular infection is caused by gram positive organisms which were susceptible to vancomycin followed by gram negative organisms susceptible to amikacin, fluoroquinolone, gram negative coccobacilli to amikacin and tobramycin, and gatifloxacin effective against both type of organisms. The information provided in this article help the clinician in formulating rationale-based empirical antibiotic treatment of bacterial ocular infections.