Microbiological findings and predisposing risk factors in corneal ulcers

To identify the current bacterial spectrum, the specific resistances to commonly used antibiotics, and the predisposing risk factors causing bacterial keratitis.

We reviewed the microbiological results of corneal scrapes and predisposing risk factors from 346 patients with bacterial keratitis. Infectious bacteria was isolated from corneal samples and sensitivity testing was subsequently performed.

In total, 346 samples were obtained from 174 female and 172 male patients (median age: 64 years; range 5-105 years). A positive culture was obtained in 43% (148/346), recovering 199 isolates. Staphylococcus aureus was the most frequently occurring Gram-positive strain (32%) and Pseudomonas aeruginosa was the predominant Gram-negative strain (10%). Patients with specific local and systemic predisposing factors had an elevated risk for bacterial keratitis with a specific risk for certain strains. The sensitivity testing revealed that chloramphenicol and fusidic acid were the most effective monotherapy drugs, with overall resistances of 0 and 12%, respectively, followed by ciprofloxacin (22%), tobramycin (23%), and levofloxacin (24%).

The bacterial spectrum is changing. The most effective drugs are chloramphenicol and fusidic acid, followed by ciprofloxacin. Specific systemic and local predisposing factors promote the risk of bacterial keratitis.