Persistent endophthalmitis after intravitreal antimicrobial therapy.

Purpose: To assess the frequency of persistent infection after injection of intravitreal antimicrobials as therapy for endophthalmitis and to determine if persistent infection influences the final visual outcome after treatment.
Methods: In a series of 42 eyes with culture-positive endophthalmitis of various types, the authors performed a second vitreous culture and injection of antimicrobial agents in 22 eyes. Repeat cultures were obtained 3 to 8 days after initial therapy in 20 of the 22 eyes.
Results: Twelve of the 22 eyes were persistently culture-positive. Organisms identified in the persistently culture-positive eyes included staphylococcal species (n = 4), Streptococcus (n = 4), Serratia (n = 1), Propionibacterium acnes (n = 1), and fungi (n = 2). Eyes in which the initial antimicrobial therapy failed to eradicate a bacterial infection had a worse outcome than those that were culture-negative on repeat sampling. Final visual acuity of 20/200 or better after repeat injection was attained in 4 of the 12 culture-positive eyes.
Conclusion: A single injection of intravitreal antimicrobial agents may be insufficient to cure some cases of endophthalmitis, and a second injection should be considered in some circumstances.