Abstract
Purpose :
Methicillin-resistant Staphylococcus aureus (MRSA) is an increasingly common cause of antibiotic-resistant keratitis. We performed a retrospective, observational clinical study to investigate the demographics, clinical management, antimicrobial resistance profile, and outcomes of patients with MRSA keratitis.
Methods :
We reviewed culture-proven cases of MRSA keratitis from 2014-2022 at Massachusetts Eye and Ear and the University of British Columbia, analyzing patient chart data and in vitro susceptibilities of the associated bacterial isolates.
Results :
Sixty-one culture-proven cases of MRSA keratitis were identified in 58 patients. The median age at diagnosis was 62 years. Thirty-seven patients were female (64%). Fifty (82%) presented with a BCVA >20/60. Many had pre-existing ocular surface disease (n=37; 61%), a history of ocular trauma (N=12; 20%), and at least 1 systemic comorbidity (N=52; 85%). Use of topical steroids and topical antibiotics immediately prior to presentation was common (31% and 38%, with 13% on both). Thirteen patients (21%) had extensive healthcare exposures in the year before presentation and 10 (16%) had a history of MRSA infection. Fortified vancomycin/tobramycin was the most common initial treatment (N=45; 75%). Fifteen cases (25%) underwent surgical management, including penetrating keratoplasty (N=5), tarsorrhaphy (N=15), and corneal gluing (N=8). The post-treatment BCVA was <20/60 for only 5 patients (15%) and ≥20/60 for 38 patients (62%; 23% lost to follow up). MRSA isolates were often multidrug-resistant (80%; MDR, resistant to ≥3 drug classes) with high levels of resistance to commonly used empiric antibiotics: ciprofloxacin (83%), moxifloxacin (76%) and tobramycin (70%). All isolates were susceptible to vancomycin in vitro.
Conclusions :
Corneal MRSA infection engendered a high risk of poor visual outcomes in our population despite treatment with the recommended antibiotic regimen. Most patients were infected with highly MDR MRSA strains even in a population with low healthcare exposure prior to the presentation. This points to the existence of community-level niches for these strains, which may be opportunistic in this setting and cause sight-threatening infection in older patients with multiple ocular surface risk factors.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.