To describe causative pathogens involved in microbial keratitis and trends of microbial isolates sensitivity and resistance to routinely used ophthalmic antibiotics.

This is a retrospective study on smear and culture samples of corneal ulcers in patients who came to Farabi eye hospital emergency ward from January 2012 to December 2018.

8912 samples were collected from patients with keratitis for 6 years, the mean age of patients with keratitis was 44.52±27.46. In patients with keratitis, 60% of cultures were negative. Pseudomonas and S.pneumonia and S.epidermidis were the most common isolates in keratitis( accounting for 10%, 5% and 4% respectively). Among patients younger than 19 years with keratitis, 41.5% were culture negative, and S.viridans was the most common isolate (13.2%) followed by S.aureus (9.5%) and S.pneumonie (8.1%). In the age group of 19-50 years, 54.3% were culture negative and Pseudomonas was the most common microorganism (15%) followed by enterobacter (7.8%) and S.epidermidis and S.aureus (4.3%). And in patients older than 50 years, 65.5% were culture negative, S.pneumonia accounted for 7.8% of isolates and pseudomonas and S.epidermidis for 6.5% and 4.8% respectively. In our study resistance of S.pneumonia to ceftazidim siginificantly increased after 2014 however other changes in antibiotic susceptibility profile was not significant.

Pseudomonas and S.pneumonia and S.epidermidis were the most prevalent isolates in keratitis respectively. According to age S.viridans was the most prevalent isolate in patients younger than 19 years old with a rising trend after 2014 and Pseudomonas was the most common isolate in patients with keratitis between 19 to 50 years of age with a decreasing trend in incidence during recent years, but S.pneumonia was responsible for most of culture positive keratitis over 50 years with a decreasing trend in incidence recently.