Clinical Features, Antibiotic Susceptibility Profiles, and Outcomes of Infectious Keratitis Caused by Achromobacter xylosoxidans

Purpose: Reports on Achromobacter xylosoxidans ocular infections are increasing, drawing attention to its emerging role in infectious keratitis. The purpose of this study is to report the sensitivities, and visual outcomes of infectious keratitis secondary to Achromobacter xylosoxidans. Methods: A microbiology database and clinical chart review was performed in all patients diagnosed with A. xylosoxidans keratitis at the Bascom Palmer Eye Institute between the years 1987 and 2014. Initial presentation, antimicrobial susceptibilities, minimum inhibitory concentrations (MICs), treatment course, and outcomes were recorded. Results: Twenty-eight patients were identified. The main risk factors were corneal graft (n = 8, 28.6%) and contact lens wear (n = 8, 28.6%). On presentation, visual acuity was 20/100 or worse in 20 (71.2%) patients. Hypopyon was present in 7 (25.0%) patients. In most cases, topical fluoroquinolones or tobramycin were the initial treatment, often accompanied by vancomycin. High susceptibility rates were found for piperacillin [100%, minimum inhibitory concentration for 90% of isolates (MIC90) = 8] and ticarcillin (100%, MIC90 = 16). Low susceptibility rates were documented for ciprofloxacin (46.7%, MIC90 = 8), tobramycin (26.7%, MIC90 = 16), and gentamicin (20%, MIC90 = 16). One (3.6%) patient suffered endophthalmitis. Six (21.4%) patients underwent therapeutic penetrating keratoplasty, and 2 (7.1%) patients had conjunctival flap surgery. Visual acuity at final follow-up was 20/100 or worse in 16 (57.1%) patients. Conclusions: Infectious keratitis caused by A. xylosoxidans is associated with poor visual outcomes. Fluoroquinolones and aminoglycosides are not appropriate treatments for these ocular infections. Further studies are needed to define the clinical application of compound piperacillin and ticarcillin eye drops.