Culture proven bacterial endophthalmitis: a 6-year review

Purpose: To assess the distribution of microorganisms isolated from patients with bacterial endophthalmitis and their antimicrobial susceptibility. Methods: Retrospective analysis of medical and microbiological records of patients with suspected diagnosis of endophthalmitis and bacterial culture-proven at the Department of Ophthalmology, UNIFESP, between January 1 2000 and December 31 2005. Results: 153 (33.9%) of 451 patients showed positive bacterial culture. A total of 155 microorganisms were isolated, 79.35% were gram-positive and 20.65% gram-negative. Staphylococcus (CoNS) (41.94%) were the most frequently isolated. The antimicrobial susceptibility for gram-negative microorganisms was as follows: amikacin 87.10%, tobramycin 80.65%, ciprofloxacin 96.67%, levofloxacin, gatifloxacin and moxifloxacin 100%, ceftazidime 85.0%, and gentamicin 80.65%. Vancomycin sensitivity among gram-positive microorganisms was 100%. S. aureus and CoNS showed 83.33% of susceptibility to oxacillin, 89.61% to ciprofloxacin and 100% to gatifloxacin and moxifloxacin. The main acquisition mechanism was postoperative (60.65%). Conclusion: We detected a low sensitivity of vitreous/aqueous culture for the etiologic diagnosis of endophthalmitis. The empiric antimicrobial therapy or prophylaxis should be active against gram-positive bacteria, particularly staphylococci. Surveillance studies of bacterial resistance are important for a better utilization of antimicrobials in this clinical setting.