Background: Ocular infections may result in severe vision and eye loss. Especially in keratitis and endophthalmitis, it is essential to identify the causative microorganism and treat it with appropriate antimicrobials. This study aims to investigate microorganisms isolated from various samples in ocular infections and their sensitivity to antibiotics.
Methods: The samples, e.g., abscess, swab, were inoculated to suitable media and at appropriate ambient conditions at 35 - 37°C for 24 - 48 hours. Sterile liquid samples were cultivated in a blood culture bottle. The isolated microorganisms were identified by classical biochemical methods and by using an automatic identification system when necessary. Antibiotic susceptibility tests were performed by the disc diffusion method and interpreted according to CLSI criteria.
Results: From a total of 167 ocular samples from 69 patients, 78 (46.7%) microorganisms were isolated. Thirteen (19%) infections were found to be polymicrobial. Three bacteria were isolated from one of them and two bacteria from 12 of them. Twenty-one (30%) of the patients were newborns, and two were children. The average age of adult patients was 55.45 ± 19.7 years. Gram-positive bacteria (n = 46, 59%) were found to be more common than Gram-negative (n = 27, 35%) among all bacteria isolated over three years. Gram-positive bacteria included Staphylococcus aureus (n = 17, 22%), coagulase-negative staphylococci (CNS) (n = 13, 17%), and streptococci (n = 10, 13%). Pseudomonas aeruginosa (n = 8, 10%) was the most common bacterium of the Gram-negative bacteria. Besides, two anaerobic bacteria (2.6%), two fungi (2.6%), and one (1.3%) Nocardia spp. were isolated. It was determined that 35% of S. aureus strains and 46% of CNS strains were resistant to methicillin.
Conclusions: Various and rare microorganisms can be isolated from ocular infections. However, it is still seen that Gram-positive bacteria are more common than Gram-negative. Multi-resistant Gram-negative rods and high rates of methicillin-resistance in staphylococci can affect treatment regimens.