Vitreous cultures and antibiotic analysis in Puerto Rican endophthalmitis patients.

Objective: To analyze positive vitreous cultures and their respective antibiotic sensitivities in patients with endophthalmitis in Puerto Rico.

Methods: We conducted a retrospective cohort study of vitreous cultures from all of the patients with a clinical diagnosis of endophthalmitis at the Puerto Rico Medical Service Administration Center in San Juan, Puerto Rico, from August 2009 to July 2010. Positive isolates were selected for analysis. A retrospective chart review was performed to establish the mechanism involved in the development of endophthalmitis.

Results: Forty-three patients underwent vitreous cultures for a diagnosis of endophthalmitis, of which 16 patients had positive cultures. Seventy-eight percent of the isolates were bacterial and 22% fungal. Staphylococcus genus was identified in 38% of patients. All of the Staphylococcus epidermidis and Streptococcus pneumonia isolates were resistant to oxacillin; 66% of the Staphylococcus aureus isolates were also resistant to oxacillin. All of the Gram-positive isolates in our study were sensitive to vancomycin. All of the gram-negative isolates were sensitive to ceftazidime. Twenty-nine percent of the post-traumatic endophthalmitis cases were fungal in origin.

Conclusion: The majority of endophthalmitis cases in our study were bacterial in origin, and the Staphylococcus genus was the most common type of organism identified. In our cohort, post-traumatic endophthalmitis was the most common mechanism leading to infection. Vancomycin in combination with ceftazidime appears to be adequate for the empiric treatment of all cases of bacterial endophthalmitis in our population. Anti-fungal agents should be considered as adjuvant empiric treatment in patients with post-traumatic endophthalmitis.