Gram-negative endophthalmitis: A prospective study examining the microbiology, clinical associations and visual outcomes following infection

Abstract

Importance: This is the largest Gram-negative endophthalmitis specific series and provides important evidence to guide management.

Background: Endophthalmitis is a sight-threatening emergency. Gram-negative infections are associated with poorer visual outcomes; however, there is limited literature pertaining to this uncommon condition.

Design: Prospective case series.

Participants: All patients presenting with endophthalmitis to a tertiary institution over a 20-year period.

Methods: Data were collected prospectively and entered into a registry. Patients with microbiological evidence of Gram-negative infection were included in the analysis.

Main outcomes measures: Final visual acuity (VA), precipitating events, causative organisms, antibiotic sensitivity profiles and risk factors for poor visual outcomes were reported.

Results: One hundred Gram-negative organisms were isolated in 97 eyes. Final VA was worse than 6/60 in 65 (67.0%) eyes at follow-up and 29 (29.9%) eyes were eviscerated or enucleated. Microbial keratitis (26.8%, n = 26) and Pseudomonas aeruginosa (34.0%, n = 34) were the most common precipitating event and causative organism, respectively. Eight (8.0%) isolates were third-generation cephalosporin resistant; of which, 7 (88.0%) were sensitive to ciprofloxacin. Preceding microbial keratitis (OR = 13.16, P = .015) or P. aeruginosa infections (OR = 3.40, P = .045) were strongly associated with poorer visual outcomes (worse than 6/60).

Conclusions and relevance: Visual outcomes following Gram-negative endophthalmitis are extremely poor, with almost 30% of patients being eviscerated or enucleated. A majority of ceftazidime resistant organisms are sensitive to ciprofloxacin, providing evidence to support the empirical use of quinolones. Clinicians should be mindful that infections secondary to P. aeruginosa or microbial keratitis carry a particularly poor prognosis.

Keywords: Gram-negative bacterial infections; antibiotic resistance; endophthalmitis.