Ten-year analysis of microbiological profile and antibiotic sensitivity for bacterial keratitis in Korea

To investigate the risk factors, microbiological profiles, antibiotic susceptibility patterns, and treatment outcome in patients with bacterial keratitis at a Korean tertiary hospital.

A retrospective chart review was performed of patients who were diagnosed with infectious keratitis and underwent corneal scrapings for cultures at Seoul National University Hospital between 2007 and 2016. Demographics, clinical characteristics, microbiological data, antibiotic resistance and sensitivity, and treatment outcome were collected.

Out of 129 scrapings, bacteria were isolated in 101 samples (78.3%). The most frequent isolates were coagulase-negative Staphylococci (CNS) (15.9%), Staphylococcus aureus (12.1%) and Pseudomonas aeruginosa (10.3%). All gram-positive isolates were sensitive to vancomycin, but methicillin resistance was found in 29.4% of CNS and 15.4% of Staphylococcus aureus. All gram-negative isolates were susceptible to ceftazidime and carbapenem while 11.5%, 3.3% and 2.8% of gram-negative isolates were resistant to gentamicin, tobramycin and amikacin, respectively. Ciprofloxacin resistance was observed in 10.3% of gram-positive isolates and 8.8% of gram-negative isolates. No significant changes were observed in profiles of microbial isolates and antibiotic sensitivity over time. Eight eyes of 101 eyes (7.9%) eventually underwent evisceration for infection control. The use of topical glaucoma medication (p = 0.006) and history of ocular surgery (p = 0.019) were significant risk factors related to evisceration.

CNS, Staphylococcus aureus and Pseudomonas aeruginosa were the most common microorganisms responsible for bacterial keratitis. The duo-therapy using vancomycin and ceftazidime should be considered for empirical treatment until the culture and sensitivity results become available.