Changing trends in the microbiologic aspects of postcataract endophthalmitis

Objective: To analyze the microbiologic spectrum and in vitro susceptibility profiles over the last 11 years of organisms isolated from the vitreous of patients with endophthalmitis following cataract surgery. Methods: Records of 497 consecutive patients treated at 1 institution for clinically suspected endophthalmitis following cataract surgery from July 1989 through June 2000 were reviewed. Results of microbiologic culture and in vitro antibiotic susceptibility testing from the periods 1989 to 1994 And 1995 to 2000 were compared. Results: Between the 2 periods, there was a significant increase in the incidence of gram-positive bacteria (92%-97% of bacterial isolates). There was a significant increase in resistance among all bacterial isolates to ciprofloxacin (23%-37%; P=.02). There was increased resistance among coagulase-negative staphylococci to both ciprofloxacin (20%-38%) and cefazolin (19%-40%). Resistance to bacitracin, trimethoprim-sulfamethoxazole, and vancomycin remained unchanged. Vancomycin retained in vitro efficacy against more than 99% of gram-positive bacteria. Ceftazidime was effective against 100% of gram-negative bacteria tested. Conclusions: The spectrum of pathogens causing post-cataract endophthalmitis is changing, and resistance to antibiotics used for its prophylaxis has grown. These findings may affect the empirical treatment of postcataract endophthalmitis, as well as the use and choice of antibiotics in patients undergoing cataract surgery.