Characterization of Polymicrobial and Antibiotic-Resistant Infectious Keratitis in a County Hospital Setting.

Area of Science:

• Ophthalmology
• Infectious Diseases
• Public Health

Background:

• Infectious keratitis is a significant cause of vision loss, disproportionately affecting low-income populations.
• Understanding the role of social determinants of health in infectious keratitis is crucial for targeted interventions.

Purpose of the Study:

• To investigate the associations between social risk factors and polymicrobial keratitis, multidrug resistance, pathogen spectrum, and clinical outcomes.
• To analyze the impact of homelessness and prior antibiotic use on infectious keratitis characteristics and treatment responses.

Main Methods:

• Retrospective study of 174 patients with infectious keratitis at a county hospital (2010-2021).
• Multivariable regression analysis to assess relationships between social, medical, and psychiatric factors with polymicrobial growth and multidrug resistance.
• Evaluation of clinical outcomes including ulcer size, visual acuity, and need for emergent procedures.

Main Results:

• Homeless patients had a higher likelihood of polymicrobial keratitis (OR 3.4, p=0.023).
• Polymicrobial infections were associated with multidrug-resistant organisms (p=0.018) and increased need for fortified antibiotics (OR 2.9, p=0.011).
• Prior topical antibiotic use did not correlate with increased risk of polymicrobial or multidrug-resistant infections.

Conclusions:

• Homelessness is a significant risk factor for polymicrobial keratitis and subsequent multidrug resistance.
• Initiating broad antibiotic coverage for homeless patients with keratitis is supported by these findings.
• Polymicrobial keratitis did not significantly impair clinical outcomes such as visual acuity or time to resolution.