Isolates and Antibiotic Resistance of Culture-Proven Endophthalmitis Cases Presented to a Referral Center in Tehran

PURPOSE: To evaluate the spectrum of organisms causing endophthalmitis and their resistance pattern to standard antimicrobial agents. MATERIALS AND METHODS: Medical records of culture positive eyes treated at Rassoul Akram Hospital for endophthalmitis during the past 5 years were reviewed. Specimens were obtained during pars plana vitrectomy or vitreous tap. RESULTS: Sixty-five isolates including 36 (55.4%) gram-positive organisms, 28 gram-negative organisms (43.1%), and 1 (1.5%) fungus were studied. The most common organism identified was Coagulase-negative staphylococcus in 16 eyes (24.6%). Among the antibiotics available for intravitreal injection, the least antibiotic resistance was for vancomycin in gram-positive organisms and amikacin and ceftazidime in gram-negative isolates. CONCLUSIONS: Gram-positive isolates were the most prevalent organisms; however, a high isolation rate for gram-negative organisms was obtained. Considering that no single antibiotic provides coverage for all of the organisms, a combination therapy using vancomycin/amikacin or vancomycin/ceftazidime seems to be useful as the initial empiric treatment of suspected bacterial endophthalmitis.