BACKGROUND: Antimicrobial resistance (AMR) determinants on the ocular surface may contribute to poor treatment responses.

METHODS: An exploratory comparative analysis of ocular surface AMR determinants, as determined by RNA-sequencing (RNA-seq), on patients presenting with corneal infections at the Proctor Medical Clinic at the University of California San Francisco in San Francisco, CA, USA, and the Queen Elizabeth Central Hospital at the Department of Ophthalmology of Kamuzu College of Health Sciences in Blantyre, Malawi, was conducted. All patients underwent swabbing of three sites on the ocular surface: cornea, ipsilateral conjunctiva, and contralateral conjunctiva.

RESULTS: Mutations conferring macrolide resistance were present on the ocular surface in 58% (95% CI 44 to 71%) of the participants in Malawi and 32% (95% CI 20 to 46%) of the participants in San Francisco. Aminoglycosides resistance genes were also common on the ocular surface with 58% (95% CI 44 to 71%) prevalence in Malawi and 21% (95% CI 12 to 35%) in San Francisco. AMR was associated with poorer visual outcomes in a subset of patients.

CONCLUSIONS: As determined by RNA-seq, ocular surface AMR gene mutations are common in patients with infectious keratitis. Surveillance may be important for infectious keratitis treatment selection as well as providing guidance for antibiotic stewardship.