May 31, 2019 Conference
Purpose: Endophthalmitis is a rare but potentially devastating intraocular infection. Aqueous or vitreous tap and intravitreal injection of antibiotics are the mainstay of treatment. Antibiotic resistance has increased in recent years, yet the majority of tap and inject procedures for endophthalmitis utilize a limited number of antibiotics. This study seeks to characterize the rates of antibiotic resistance among isolates from culture- proven endophthalmitis cases.
Methods: Retrospective review of all inpatient and emergency dept. consultations at a tertiary care hospital for cases of suspected endophthalmitis over an 8-year period (2010-2018). Records were reviewed to identify cases of culture-proven endophthalmitis with documented culture sensitivities.
Results: We identified 79 cases of presumed endophthalmitis, resulting in 62 tap and inject procedures and 20 positive cultures with an identified organism and sensitivities. In total, 98 samples were obtained, including 63 aqueous (64.3%) and 35 vitreous (35.7%) samples. 16 of 63 aqueous samples resulted in a positive culture (25.4%) and 9 of 35 vitreous samples were positive (25.7%). There was no significant difference in the rate of culture positivity between aqueous and vitreous samples.
Positive cultures included 8 strep species (40%), 5 staph species (25%) and 7 others (35%) including Serratia, Klebsiella and Fungi. Resistance to ceftazidime was most commonly encountered, affecting up to 50% of staph and serratia species (figure 1). Vancomycin and ceftazidime were the most commonly used antibiotics, given in 88.7% and 80.7% of injections respectively. Empiric coverage was appropriate in 95% of cases, with the identified organism being susceptible to one or both of the antimicrobial agents being used. There were no cases of MRSA or vancomycin resistance identified in this cohort.
Conclusions: Real world culture yield from aqueous and vitreous tap for endophthalmitis are poor, with approximately one quarter of samples positive in this series. Empiric use of vancomycin and ceftazidime continues to provide excellent coverage for the majority of cases of bacterial endophthalmitis despite resistance to ceftazidime.