Multicenter retrospective case series (2005–2022) of 70 eyes in 67 patients with culture-confirmed MRSA keratitis at two North American centers, evaluating clinical features, antimicrobial resistance patterns, genomic epidemiology, and visual outcomes.
85.7% of isolates were multidrug-resistant (MDR); fluoroquinolone susceptibility was very low (moxifloxacin 19.7%); all isolates remained vancomycin-susceptible (MIC₉₀ 2 µg/mL). Genomically, CC5 (68.3%) and CC8 (29.2%) dominated. Visual outcomes were poor — 85.2% of patients with follow-up had final best-corrected visual acuity worse than 20/60.
Retrospective design limits causal inference; whole-genome sequencing was performed on only a subset of isolates (n=41); only 25.4% had recent healthcare exposure, so community transmission dynamics remain incompletely characterized.
Empiric fluoroquinolone therapy is likely inadequate for MRSA keratitis given very low susceptibility (~20%); vancomycin remains the mainstay of topical treatment and all tested isolates were susceptible. Early aggressive management and antimicrobial surveillance are essential given the high rate of permanent vision loss.
