• PURPOSE: To investigate the spectrum of organisms causing culture-proven endophthalmitis and their sensitivities to commonly used antimicrobial agents. • DESIGN: Retrospective, noncomparative, consecutive case series. • METHODS: Medical records were reviewed of all patients with culture-proven endophthalmitis at a single institution between January 1, 1996, and December 31, 2001. Endophthalmitis categories included postoperative, posttraumatic, endogenous, and miscellaneous (for example, keratitis). The outcome measures included intravitreal isolates identified, antibiotic sensitivities, and category of endophthalmitis. • RESULTS: In all, 313 organisms were isolated from 278 patients during the study interval. The most common organisms identified were Staphylococcus epidermidis in 27.8% (87/313), Streptococcus viridans group in 12.8% (40/313), other coagulase-negative staphylococci in 9.3% (29/313), Staphylococcus aureus in 7.7% (24/313), and Propionibacterium acnes in 7.0% (22/313). Overall, 246 of 313 (78.5%) isolates were gram-positive organisms, 37 (11.8%) were gram-negative organisms, and 27 (8.6%) were fungi. For gram-positive organisms, sensitivities were the following: vancomycin 100%, gentamicin 78.4%, ciprofloxacin 68.3%, ceftazidime 63.6%, and cefazolin 66.8%. For gram-negative organisms, sensitivities were the following: ciprofloxacin 94.2%, amikacin 80.9%, ceftazidime 80.0%, and gentamicin 75.0%. Fungal isolates were Candida species (9/313), Aspergillus species (9/313), and other molds (9/313). Among the endophthalmitis categories, the most frequent organisms were the following: (1) acute-onset postoperative: S epidermidis, 46.9%; (2) delayed-onset postoperative: S epidermidis, 22.7%; (3) delayed-onset bleb-associated: fastidious gram-negative rods, 20.4%; (4) posttraumatic: S epidermidis, 20.8%; (5) endogenous: Aspergillus species, 20. 8%; and (6) miscellaneous: molds (other), 36.4%. • CONCLUSIONS: In considering antibiotic treatment of endophthalmitis, it is important to recognize that no single antibiotic provided coverage for all of the microbes isolated from eyes with endophthalmitis. Combination therapy is recommended as the initial empiric treatment of suspected bacterial endophthalmitis. Appropriate history and characteristic clinical features may justify the use of initial antifungal agents. Knowledge of the most frequent causative organisms in various categories will help direct appropriate initial therapy.
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