Pathogens involved in microbial endophthalmitis and trends of microbial sensitivity to routine antibiotics

Purpose: To describe causative pathogens involved in microbial endophthalmitis and trends of microbial isolates sensitivity and resistance to routinely used ophthalmic antibiotics. Methods: This is a retrospective study on smear and culture samples of aqueous and vitreous humor in patients who came to Farabi eye hospital emergency ward from January 2012 to December 2018. Results: 2999 samples were collected from intraocular origin during 6 years (1231 samples from aqueous humor and 1768 samples from vitreous humor). Mean age of patients were 59.17±21.30. 75% were culture negative and S.epidermidis (6%) and S.pneumonia (4%) were the most prevalent microbial isolates. In endophthalmitis patients, younger than 19 years, 69.3% were culture negative. S.viridans ,S.pneumonia and S.aureus accounted for 13% ,7.3% and 2.6% respectively. In 19-50 year old patients , 78.7% were culture negative , and S.epidermidis (9.1%) and S.viridans (3.7%) were the most prevalent microorganisms. In patients older than 50 years of age, 76.4% were culture negative and S.epidermidis (6.6%) and S.pneumonia (4.4%) were the most common isolates. In our study resistance of S.pneumonia to ceftazidim siginificantly increased after 2014 however other changes in antibiotic susceptibility profile was not significant. Conclusion: In our study 75% of culture samples of intraocular fluid of patients with intraocular infection were negative and S.epidermidis and S.pneumonia were the most common isolates (6% and 4% respectively). In patients younger than 19 S.viridans and in older than 19 S.epidermidus were the most prevalent microorganism detected in cultures.