Visual Outcome, Microbiological Profile and Antibiotic Sensitivity of Infectious Keratitis in a Tertiary Referral Center

Abstract

Purpose : Known to cause devastating loss of vision and corneal abnormalities, consequences of infectious keratitis and corneal ulcers could potentially be avoided by immediate treatment with appropriate antimicrobial eye drops. Treatment is chosen based off identification of corneal infection and antibiotic susceptibilities. Because culturing corneas may take days to weeks, the mainstay of treatment is empirical therapy with broad-spectrum antimicrobials that are started before culture results return. We aim to record the microbiological profiles with associated antibiotic susceptibility patterns isolated from corneal cultures in patients with infectious keratitis, as well as visual outcomes over a 5-year period.

Methods : A retrospective analysis of medical records of patients who presented to UMMC from 1/1/2014 to 12/31/2018 with keratitis or corneal ulcer were included in this study based off diagnosis codes.

Results : Of 563 corneal infections analyzed, 202 (35.9%) had positive cultures. The most frequently isolated organism was Coagulative negative Staphylococcus/Staphylococcus epidermidis (27.2%), followed by Pseudomonas aeruginosa (18.7%), and Staphylococcus aureus (11%). Pseudomonas aeruginosa was isolated in 37.2% contact lens wearers. We found that 93.3% of gram-positive cultured bacteria were susceptible to vancomycin with no resistance, and 81.8% of gram-negative bacteria were highly susceptible to tobramycin with no resistance. Regardless of treatment, 19.8% of patients needed some type of additional procedure, with the most common procedures being corneal transplant (49.1%) & evisceration (11.6%). Vision improved at 1 month in 18.8% and 24.3% of eyes with gram-positive and gram-negative keratitis respectively; it improved at 3 months in 10.3% and 9.9% of eyes with gram-positive and gram-negative keratitis respectively.

Conclusions : CNS, Pseudomonas aeruginosa, and Staphylococcus aureus were the most common microbes causing infectious keratitis. Pseudomonas aeruginosa remains the most commonly identified organism in contact lens wears. The empirical treatment of vancomycin and tobramycin used at our institution remains an excellent treatment for these microbes based off susceptibility and resistance patterns. After accounting for patients lost to follow up, most patients’ visual outcomes improved the most at 1 month then at 3 months after treatment.

This is a 2020 ARVO Annual Meeting abstract.

 

Microorganisms